Mike, will you be selling out your home if you own? Do you already have a rv. ,tow vehicle ? Will you travel alone? IMO most anyone can afford it you just adjust to what you have. Food is bought regardless so its a break even. Fuel will run more but not a lot if you stay in one location for awhile. Water, sewage and electricity is furnished with the campsite so no extra bills there although some extended site have electric meters. There will be repairs on the rv just like a home. As Len said Kirk has a great website with cost. Only you can decide if you can handle it in the end. Good luck and welcome to the forum
I try to list actual expenses of pretty much everything that we do, since life as a fulltimer is really not that different from living any other lifestyle, when it comes to what you spend your money on. Since we have not had any installment payments in more than five years now. the only item that is not in our expense report on the website is savings. Strangely enough we do manage to save a little money!
One item that I would draw particular notice to is the cost of our RV sites. It is very low because of our lifestyle of volunteering for our site. For most people that is the item that probably is least helpful. Of course, the serious boondockers would also have a very low number of nights of paid campsites. I hope that what we have does help some folks. We have lived this life now for nine years, but believe that anything older than five years is probably not very helpful.