You don't know how small is too small until you try living in it. The longer you live in it, the more likely it will be too small.
With what you are considering doing with a motorhome, you will likely still be towing, another vehicle for getting around at your destination. I get by not towing when continuously traveling, but when going to a destination, I need transportation. Sometimes fellow campers, sometimes family, sometimes a borrowed car, sometimes my wife followed me in her car. Since she died, more often now I am towing a car, bought for the purpose. I am on my second one.
If you are always going to the same warm place for no more than two months, there are options that can be less expensive and less confining than ownership of a small RV, motorized or towable. There are warm places, not in resort areas or urban centers, where rentals or even second home ownership can be less expensive than ownership of a motorhome comfortable long term for a family of four. One problem might be that some of these tend to be 55+ communities, another is that small rural communities in the South can be a major culture shock for folks from other parts of the country (which is why snowbirds tend to congregate in snowbird communities).