Speed is your only protection. Don't. It will be a royal pain but the only, and I do mean only, way to avoid damage from the road surface is to just go slow. It'll either be that or reattaching the cupboards when you arrive..and get back home. One thing might be to drop the air pressure in your tires, but then you run the risk of stone punctures. Plus you will need to have a compressor with you.
Another thing to be aware of is the dust that will get all over everything. It will get in thru any small opening and by the time you get your 15 miles in? and out, eh....There are ways to mitigate the dust..maybe. Your RV will likely have one or more Fantastic Fans. You can reverse the air flow so rather than sucking out..blowing in, thus creating a positive pressure inside. But really? just plan on devoting a couple hours to doing a thorough clean. Put the bedding and clothing in large plastic bags.
As far as A or C? You need to decide which design works for your family.
Where do you like to go?
Gary Haupt
BC