Rules vary considerably from place to place. I don't believe they can discriminate against you with a handicapped son. Check with the state laws and federal law.
We are in SE FL which has a bunch of 55+ and other communities. Since we aren't welcome in those 55+ because of our age or because of our daughter we don't go there (don't want to live in one regardless). Plenty of other places, ownership parks and other types of parks that don't care. You can own, rent, short term / long term it doesn't matter. This is an area with incredibly expensive land so RV parks aren't a dime a dozen and we still have choice. Much less in AZ where land is more abundant and cheaper.
Bottom line is do your research before you plant your root down. Backup plan is always nice so if Park A doesn't' work out while renting you can do B or C etc.
If you find something you really like you can consider an owner park as a home base and travel from there. I'd suggest renting before buying. Keep an open mind to the area as well. If one area isnt' working check out another.