Ok so the installation went flawless.
What I did:
followed this vid:
- deburr the edges of all the spoke holes
- went for 21mm Schwalbe tubeless tape which is the same size as the original rim tape (which I removed, of course) -> it fits my 17mm width rims perfectly
- used a blowdryer to soften the tape while applying on the rim and avoid bubbles (I hadn't any)
- used a patch of gorilla tape at the valve entry before perforating it with a big needle and install the valve (no cutter for me to keep the hole round)-> I did the test of perforating a piece of Schwalbe tape and it tend to tear a bit so I made it stronger with a tape which has a weft already
- use a headlamp (trust me, it helps).
What I didn't do:
- use a standard butyl tube first with the tubeles tape installed to help making the tape stick without bubbles -> wasn't needed with the Schwalbe tape + hair dryer
- use 2 layers of tape -> I used one layer only- because it's really thick and Schwalbe states 2 layers are not needed
- use baby powder -> there was enough on the latex tube and the inside of the GP5000 tire is very slippery already
- use any tool to mount the tire (to keep the tube safe). I had no problem whatsoever to mount the GP5000 on the rim
To me the main thing is to inflate the tire very slowly and keep an eye at the bead and make sure the tube isn't trapped under it. I honestly thought it would be more complicated based on everything I read so it's worth trying it by yourself. Now I'll see how it holds up and will let you know if I didn't fall of a cliff because my tubes popped.