I wouldn't lock in a venue sight unseen. Best bet is to select a few destinations and stay for a few days to get a feel for the place compared to your needs and feelings, more important, how is the place and your neighbours? While some places get busy in the winter, we've never had a problem moving around in Arizona, New Mexico or California (with the possible exception of March break week(s)).
It took us almost 3 years to find a place we fell in love with and we now go back there for 3 months each winter (but we still spend 2 months enjoying other campgrounds getting to and from our "destination")
By the way, that destination is Borrego Springs California, about 3 hours north west of Yuma Arizona, a community of about 3,500 people. Only downside is really good shopping is about an hour away in Palm Springs or Brawley but the location is worth the downside.
