Thanks for the replies. I think the question has been answered. I play 4.6+ singles (not a ton of matches) and doubles (lots of matches) in my club but there seems to be an awful lot of rating inflation. Few among the guys in this club league play USTA NTRP tournies, but some do play USTA league and a few do age group tournaments. Two of the guys I play singles somewhat regularly with are USTA guys. One is a 4.0 with a 50% winning record in USTA singles. At the risk of sounding less than humble, I beat him pretty easily. The other guy was bumped to 4.5 and has a losing record in 4.5. I have to work my *** off to beat him, but beat him I do. The 4.0 guy tells me that I shouldn't self-rate at 4.0 b/c I'll get a rep as a "sandbagger." The 4.5 guy tells me I should play 4.0 and expect to bring home a trophy or two. I know he misses 4.0, and he's pretty salty about the bump. He's far more interested in tennis as a vehicle for athletic domination than I am.
From my point of view, I just want to rate correctly. I don't not super interested in winning a bunch of matches in a walk, nor do I want to be cannon fodder. I wouldn't call myself match tough in singles by any means, and I'm not particularly certain my body will be able to take multiple singles matches over a weekend very often. But I do want to try my hand and see where I stand. It seems much safer to self-rate potentially too low than too high. This seems to be what most of you are saying.
As for doubles, my prospective doubles partner is a USTA 4.5, and he wants to play 4.5 and open. If I want to play with him, I'll need to play 4.5 doubles. Sounds like this won't affect my singles rating. Based on the replies, I plan to self rate at 4.0. Many thanks.