Some misunderstandings with the replies. I wasn't clear--I'm using tubes for the moment. Not sure about tubeless yet. It's just that the wheels and tires are tubeless (HED Ardennes Plus and Vittoria Terrano Dry TNT).
In any case, there seems to be a concensus that I need a double wrap of 24mm tape. So I'll leave that.
PS - regarding just levering the tire on. Yes, I've managed to do that a half dozen times with the Contis I've been using. But when I tried with the Vittorias I got one on, and then the second one broke my Pedro's lever, which has never happened to me before. I can set any ordinary tire with no levers at all. I'm going to go at it with the Kool Stop jack this morning, but I really don't want to have do deal with a flat on the road.
PPS - I also have experienced the "stretch" that seems to happen after you've mounted them once and ridden them.
Last edited by showlow; 03-27-20 at 09:07 AM.