To kind of summarize...
Our first RV was only 15' long, we'd fit almost anywhere. Each successive RV has gotten bigger, our "retirement home" being 43' long. Yes, with each increase in size, there will be sites/parks we'd no longer fit on, but even up to today we've always found accommodations near where we wanted to visit, it just may not be in the public park campground (although many are upgrading).
This is no longer a weekend adventure rig, you'll be living in it. Only you know what kind of comfort you want in your new home. Life is full of compromises, this is one. Access to most county, state or federal facilities, or maximizing your travel and living comfort - or something in between.
Happy hunting. Your dream rig is out there, whatever you decide.
Jay & Peggy Monroe with Dolly
Can't take it with you - don't plan on leaving any behind
2016 Newmar London Aire 4553, Spartan chassis
Wrangler Unlimited toad