i won't quote as to reply to someone specific. only one here - thanks, shelbyfv - had a positive take to the enterprise and finally understood the details i mentioned in the first post. i forgot to mention from the beginning that i'm on a low budget so i can't be bothered with tubeless tape which would have been thin and also not removable for cleaning up the rim properly from time to time. the wheel is made as strong as possible and only if the electric motor hub is somehow damaged and beyond repair will the spokes be slacked and that will be with tools so that the rim will go to make another wheel it such a case. it's a disc wheel so having no braking surface this wheel is virtually guaranteed to work for decades provided chemicals do not mess up by contributing to stress corrosion cracking. that's why i want the tape to be easily taken off, to be able clean the rim in the space tension through flexural stress has any rim vulnerable, regardless of the tension the spokes have, uniform or not, high average or not. so i see no reason to have the rim under a lower compression. you want the rim to have a proper compression so that the radial deflection is low under load and the spokes never go slack. having 250mm spokes of the heaviest kind from the KTM factory i had to set a high tension and the advantage of having spokes less vulnerable to hits (vandalism, rocks hitting them etc.) is not a thing to be disregarded. if i had thinner spokes, at least on the NDS i would have set a lower tension.
the rim is clearly a modern 29er rim - 622 bead diameter. so the only particularity to this wheel is the higher compression and therefore the higher strain, the diameter being more than 1mm shorter. a normal tape would not sufficed and the tire is a Conti Race King which - i have to tell people around here - lets in mud easily for the sake of easier than normal fitting, even for tension of the spokes as the books say (120kgf but most people measure that with the tire uninflated and that is usually for a 32h rim).
so, if anyone tells me to let the spokes looser for the sake of having a less shorter diameter/circumference of the rim is clearly not in the know about wheels. and if anyone says such a high tension is to be avoided either doesn't know crap about my needs/environment or doesn't know crap about mechanics or is lazy to figure out that you can have the cake and eat it too if you achieved the right spoke tension variance with the right low radial runout (0.1mm total) for the average DS tension you have set as an optimum.
a good advice i would have considered would have been about the maximum width of the extra butyl layer - about the same as the external rim width i guess, i forgot to measure the final adjustment. but YMMV (if somehow you find yourself needing to do so with a high tension wheel with many spokes) because the channel where you insert the nipples can be lower for some and higher for others.
so... here's the final update - i guess:
the rim is the "Oval" brand and it's a really nice rim that would have had a just about right diameter for usual tires. it certainly can withstand 150kgf DS tension in the 36h set if it withstood more than 180kgf (forgot to measure when i did the straightening) with the tire at about 3.8 bar (55 psi).
the rim tape was not fitted correctly before i bought the bike - having the wheels messed up i bought it kinda cheap and i knew i can fix them properly and do a better job than KTM did at the factory both at choosing the components, including the same Alpine set of spokes for both flanges, and at wheelbuilding. the guys there have no clue about bicycle wheels. i had to work for a front 32h wheel having DT Rev spokes, DT Prolock nipples with flat/low spot wheel that had the tension just a bit higher than 70kgf average both sides (no disc). i cursed them for choosing Prolock nipples and i replaced them with brass nipples i carefully lubed to achieve just a tad under 120kgf average tension with low radial runout and low spoke tension variance. (slightly offtopic, just to show that i'm used to see people not having a clue about what makes a wheel both strong to impacts and safe/durable in the long run).
so, the provided rim tape had no use as it was before except to be cut narrower than what the width was. the width was not good enough when originally fitted and so it had messed up and i either would have had it replaced with a much more thicker one or just add the wide butyl layer i just added tonight. which is nice and ensures the pressured tube does not rub against a rigid tape. nor does the tire move around, forcing the tube to rub against a normal rigid or slightly abrasive tape (cloth).
the cut portion of the 26" inner tube makes the wheel just 50 grams heavier, i don't give a crap about that, it's totally worth it; anyway, the total weight of the bike is way over 20kg. a thicker rim tape as needed would have added some weight anyway. the butyl layer not only ensures a tight fit but also a relative ease getting the tire on the rim and would impose 1-2 tire levers only when getting off which i never do on the road because i don't want to carry pump, levers, patches or extra tubes but i'd rather have some Marathon Mondial or some tire liner with a larger than 2" tire in the rear and a 1.6" Dureme front that is puncture resistant. it's an electric bike you do not use more than 20 miles in one day.
i had the surprise to find the cut portion tube to be under any tension (not a really tight fit) so i made sure it does not get narrower than the rim seat so tht it climbs just so a tiny bit of space remains to the rim hook;
the work was tedious but i'm glad i did it;
the hard part was cutting it patiently with scissors, without having extra tools to make sure the width stays the same;
i mounted the tire using just my hands, no levers required, that's because...
butyl is compressible and so...
the interface between the tire and the rim is better sealed now against crap coming in.
ghost punctures, several
ghost factors involved. ghost busters! i do not like to be under sod's law.
the wheel is now with a inner tube that had a puncture repaired and unfortunately i only figured out that the patch is best applied after you take the plastic cover off from it by bending it several times and using something to cut the plastic thin tape in the center and carefully getting it off and then apply the patch in such a manner as to stretch it properly to take the best shape and have smooth transitions. any curvature on a patched tube is to be smoothed out and that is not possible with the plastic tape still on; also the drying up of the solvent is faster this way.
i thought to point this puncture repairing tip as not many people figure this out on their own easily and it's a very useful thing to do. i read about this just now, right before mounting the tire, after so many years..
https://www.bikeforums.net/8994869-post32.html
so, the wheel is now under a light pressure now and will be let to dry up completely
i'll make the test ride tomorrow i guess.