I'm guessing you are looking at a new or fairly new DP - less than five years old.
As mentioned above - DP maintenance costs can be expensive - but not that expensive. Unless you have an old worn out rig requiring several major repairs each year.
Full-time RV costs run very close to what your cost ran while living in a S&B home. Food will be much the same, entertainment much the same, cell phones - the same, internet likely a bit more expensive, TV will be near the same.
Clothes, haircuts/ beauty shops, medical, and other costs will be near the same. Your clothing budget might be smaller because you have to practice one in / one out (if you buy a new pair of pants - you need to get rid of a pair - otherwise the coach becomes a full closet with no room for people).
RV insurance costs are not terribly expensive.
I think a person would have to work very hard to spend as much per year on RV park/ campground costs as a mortgage and property taxes. (Of course if you don't have a mortgage now - you have to watch how much the CG will costs.)
It is easy to average $30 per night or less with an RV. Though some places are obviously going to be a bit more expensive. Camping club memberships as mentioned above can help control costs - if you use them.
Military bases help us go low cost for a month or so, and allow a higher cost month to fit in a much smaller budget.
Fuel is the really big variable. 10,000 miles a year traveling will be about 1,350 gallons of fuel - $5,400 of diesel, $4,500 of gasoline. But 20,000 miles per year would double that cost, and 5,000 miles a year would halve the costs.
How far do you plan to travel?
We want to go coast to coast and to all four corners of the lower 48, and to Alaska. Doing it over two or three years will be very expensive. Doing it over 10 years - not that bad.
I see you planning to come back to your home base every year or every few months. That can make a west coast trip more expensive. Might be cheaper to put the RV in storage for a few weeks at a military base in California and fly home than pay for the fuel, driving time, etc of a return home.
50K is certainly a very adequate budget. But plan to spend no more than $3,000 or $3,500 per month most of the time. That will allow room for the expensive special months/ places.