Just for sake of closure will mention I ended up with a 50mm Marathon Supreme on the Rhyno Lite rim.

Seems to have worked pretty well, though coming from something with a lot larger heavier tire I sometimes wonder if I should have just gone with a cheaper tire having more rotational mass for a more familiar feel - it's so light that when climbing it nearly stops dead at the dead zone in cranks, without any coasting through at all. But I got through almost as much of the locally notoriously muddy trail gap on it, only dismounting for one additional trouble spot that I might have attempted on my bigger knobbier tired wheel.

Turns out a friend runs Hookworms on Rhyno Lites in several wheel sizes, so if I ever decide I want something huge, that's a proven option too (frame has ample clearance).