There are two ways of looking at full time RVing, depending on what you're trying to get out of it.
If you're looking at parking in pay campgrounds, it won't be cheap. A lot of full timers agree you need an income of about $60,000 a year. Unless you have property to park on, or friends and relatives who can offer a full time place to park.
The other way of approaching the problem is often referred to as vandwelling. Vandwellers often use BLM land out west, which permits free camping. You pretty much want a camper set up for boondocking: which would most likely include a good set of storage batteries and a solar charging system which keeps the batteries topped up for long stays without electrical hookups. A good reference site is:
Vandwellers aim to live on the cheap, for various reasons - sometimes in converted bands, trailers, box trucks, whatever. This sounds like it may be what you are aiming for, since you are working with a couple of 'meager' pensions. The above site has a lot of good and experienced people to offer information. They're also a tight group who help each other out. Some of them will do a solar install for you if you buy the components.
There are quite a few women solo vandwellers, as well - several in their 60s. They can discuss safety issues. Do you NEED an RV with a shower and toilet? Not really. Depends on how comfortable or proud you are. Can you go potty at night in a bucket of cat litter? Can you get a $30 dollar a month gym membership to use the showers and other amenities? Assuming you're staying in one area. If you're travelling, Walmarts (most) and Truck stops permit overnight parking.
Check out the site. Talk to people who live the lifestyle. Decide if it's for you or not.
I'm a long time member of RV.net as well, but you're not going to find a lot about inexpensive full timing there. That's not what that site is geared for. You will get a lot of good information on RVs.
We're leaving next week for a 3 month tour of Alaska and the Yukon. We avoid campgrounds unless necessary. Good luck with your endeavor.