As someone else mentioned, living in an RV can be inexpensive; travelling in one maybe not so. It depends on your definition of travel. If you stay in one spot, or at least a month in each location, than you will likely get the best rate for that particular campground/RV park. However; most state and federal campgrounds do not give weekly or monthly rates and may have stay limits. At 60 years of age, you will not be eligible for an America the Beautiful Senior Pass; so the 50% discount on campground fees that many retirees get that reduces their costs at Forest Service, BLM, Corps of Engineers and other federal campgrounds will not be available to you. In my experience, $100/week and $250/month are about as good a rate as one can get at a commercial campground/RV park. $20/night at a public campground, which in my experience is the low end for at least electric without a discount, comes out to $600/month.
As an example; during September/October 2013, a 6 week trip around New Mexico was a little over 1,100 miles destination to destination according to Streets and Trips. In and around would have to be added to that. Total fuel cost was a little over $1,000 and campground fees about $1,100.
As mentioned, some fulltimers and snow birds workamp or volunteer to reduce their site costs. How many hours per week are required and for how many weeks/months varies with each location/agency.
Boondocking is also frequently mentioned as a means of cutting costs. However, if your Motorhome is not already equipped with a pretty robust solar system and battery bank, you will need to run the large onboard generator a fair amount or invest in a small inverter generator. Power and water conservation measures for extended boondocking are more appealing to some than others. If you want/need internet while boondocking and use much data, cellular data plans can get pricey. If you want TV and stay in the real boondocks, than satelite TV is often the only option and yet another cost.
If your house is in a part of the country that gets very cold, you may or may not be able to save all that much on heating costs unless you can drain all the water lines, water heater, etc. that might freeze. The more services that you can suspend while you are gone, the lower your costs will be.
Hope this helps in your decision process.