I'm with Miles. I think you need to do this in layers, since I think you are going to find out that living full-time in an RV may not be more affordable than where you are living now.
But first, in your introduction you mention being an older person with disabilities. Can we assume you have already looked at RVs and climbed the stairs and maneuvered through the walkways? Have you checked heights of cabinets to make sure you can reach everything? Do you have the agility to open all the lower compartments and stoop down to get in them? Sometimes you have to really be agile to get into the compartments if they get blocked by a water hookup, etc.. You need to get this sorted out in your mind before you go any further in your pursuit.
Frankly, trying to give any estimate on probable expenses of a hypothetical RV is impossible. That is one reason most of us paid a bit more upfront so that we would minimize the chances of a breakdown (at least in the near future after purchase). I have not been in the market recently, but $10K for a rig with slides is already taking a chance on problems. If your budget is in the $10K range I would suggest focusing on rigs without slides and take more time to enjoy the outdoors. Some years back, we rented a 30 ft rig with a great floor plan and no slides and we had room for 5 of us on a 2,500 mile trip. I could have easily lived in that rig.
In your price range you are looking at a gas rig. This will be an advantage for you since maintenance issues are usually less on gas rigs than they are on diesel. As a new person to the RV world you certainly want to find a local inspector who can take a look at any rig you want to buy. This would be your best insurance against some surprises right off the bat.
Every RV made can get you from one coast to the other. Those who complain about not enough power to get up a hill should probably find another source of recreation. Yes, you may have to slow down a bit when you climb a hill. But, so what! Just ignore this argument.
Don't worry about things that can be added or easily modified after you purchase your home. Things like TV, satellite and all that stuff are nice to have from day one, but really should not be what you base your purchase on. The three most important criteria for buying a motor home are: 1) floor plan, 2) floor plan and 3) floor plan. Get this wrong and nothing else really matters.
Don't get wrapped up in your shorts about towing service. Get Coach-Net which is about the same amount as AAA. Sleep well knowing you are covered.
But, I am getting ahead of myself. I think by the time you get this far you may find that the RV life style is a choice of preference versus a choice of cost saving. I don't think you will find the latter here.
It will be interesting to see what you find.
Bob