We travel from Alaska to Arizona and back every winter in our pickup camper. Its pretty rare we stay at a campground on the way…….maybe once every week or so to do wash and empty tanks. BLM offers lots of free/low cost camping. National parks withe the senior card offers low cost camping. For example we stay at Death Valley for $7 a night. Here are some good sources of info for free/cheap places….
https://freecampsites.net/#!(33.45894,+-114.39538)
https://www.campendium.com/free-camping
We keep a 5th wheel in AZ year around and use it as a “home base” and travel around in our pickup camper. The place we are at now costs $1385 a year. http://wagonwestrvpark.com/
We spent 12 winters in Bouse. Only reason we left is they raised their yearly prices, but still have some of the best monthly rates around. https://desertpueblorv.com/
You might reconsider a 40 ft 5th wheel for full timing. It will limit the places you can stay. Basically you will be “full timers” if your going to camp for 5 years. You should check out the forums where full timers hang out. They have lots of good advice from experience.
https://www.rv.net/forum/index.cfm
2016 3500 HD Durmax
1994 S and S 9.5' Camper (SOLD)
1999 S and S 9.5 Camper
