Andrew R Stewart 

First comment is about what's good enough. How perfectly molder are tires (and that's not mentioning sew ups)? I've worked to about 1mm of trueness. I balance this with the spoke tension evenness. Both are factors to a good wheel. The trueness is what's judged right away. The spoke evenness is what is noticed later, many mile later.

Try back lighting the indicator/rim gap. Looking for a sliver of bright light is more black and white then looking for a dimmer white back round growing and receding.

I agree with the dial indicators not being everything to all. The stand's rigidness is vital to minimize the needle shake. How the tip and rim is dealt with also influences the needle's jerkiness or shake. I've used dials a few times over the years and the same issues repeat. Recently I got the Park set for my TS-2.2 (not the TS-3 the set was made for). I modded the mounts and once again played with a dial set up. Once again I find the same issues that made me not bother with them for decades. (But if one doesn't revisit the past the lessons learned back then can be forgotten). I will absorb the dials into my other fabricating stuff.

Don't overthink truing too much. By the time you've put on a few miles that "within x thousandths" becomes a lot more with real life. It's the wheel's stability (it's remaining relatively true, round and dished) that really maters, not how true it is when on the stand. Andy