A quick followup. The TM-1 came. I followed advice from this thread and found an old 26" wheel that will never be used again, labeled three spokes on it with tape, and then measured their tension and wrote it down, so that in the future I can compare the TM-1 with that wheel and see if it's changed. Whether it's strictly accurate or not I don't know, but as long as its consistent I'll be happy.
I de-tensioned all the spokes on my new wheel, loosening the nipples until I could see the first thread on the spokes. I went around the circle first doing three full turns, then two full turns, then one full turn, and as soon as I had some tension I picked the tension of the first spoke after the valve hole, and went around the circle and brought every spoke to that same tension (a 17 on the TM-1, or about 70kgf). Then I proceeded a half-turn at a time or so, picked a new tension (20 on the TM-1 scale), brought them all up to that same setting, then finally went around the circle and brought every spoke up to a 21.5 on the scale, which is around 110 kgf.
When they were all within the margin of eyeball on the scale at 21.5, I put the wheel in the front fork of the bike and looked at the wobble. There was no radial wobble that I could detect, and the total lateral wobble amounted to around 2mm or so. As I rotated the wheel I adjusted the front brake pads so that at the high point of the wobble, the brake pad touched the wheel and stopped it. I'd then do very small tweaks of tension (like 1/16th of a turn, sometimes as much as maybe 1/8th of a turn) starting at the point where the pad stopped the wheel and feathering the adjustment away from that point two or three spokes in either direction. I'd then respin and examine what the change had done.
In this way I kept the radial wobble of the wheel at an undetectable level (doesn't look like any to my eyes) and I nudged the total lateral wobble down to less than half a milimeter or so. I decided to call it good. I haven't measured the tension on the spokes since I did this, mainly because I didn't want to get sucked into the mind trap of thinking I needed to go back and tweak it a lot more in the interest of consistency. I started the truing with the spokes as nearly identical in tension as I could judge on the relatively crude scale of the TM-1, and then trued the wheel using very small adjustments. So I think that whatever small variance in final tension may exist, it won't be all that large, and probably couldn't be helped. At least not by someone of my newbish skill level.
When I rode the wheel again yesterday afternoon I heard not one single ping from it. I'd squozen spokes together and whatnot as I tensioned it up, and heard several pings during that stress relieving, so that by the time I rode it, apparently it was good. The wheel feels solid, stiff, confidence-inspiring, the 25mm GP4Ks tire grips like it was glued to the ground, corners smartly, etc. And I no longer worry that my 270ish lb self is taking my life into my own hands riding a 19mm wide 20-spoke Racelite wheel as hard and fast as I often do. I recall hitting my max-ever downhill speed of 53mph going down a short, steep descent here in AZ and thinking holy crap, if anything fails on my bike ride now I'm literally gonna die. I think that remote possibility just got a little further away with this new 32h wheel.
Thanks for all the advice!