Don't know of anyone, should be lots of after-market memberships around for sale. Would expect the problem to be getting one that fits where you want to base out of.
Just google 'thousand trails memberships' and that ought to bring some up.
Have you looked long and hard at this? Several have mentioned many of the CGs are not being maintained well, but no personal experience.
2016 Tiffin 40 QBH
2015 38RSSA, traded
2005 TK3 #1869, 10 yrs of memories,
2017 F450 KR--one more Ford is it
2009 F450 4x4-died; 2010 F450-retired