We traveled with 4 dogs for 6 months in our RV.
(3 Shelties and a Rotty...a 100 pound, VERY energetic Rotty.)
They
sell "kennels" that are sections of chain link fence bolted together.
These are pretty easy to attach to an RV.
If you use
chicken wire to go around the bottom of the RV, you make the underneath an instant, cool spot for them.
The only thing I worried about was when gone, having a fire.
Building a "Habitrail" out of fence so they can get 30 feet away from the RV, but still be retained.
You can get two 10X10 enclosures and enough fence to make a very secure setup for the pup friends.
Leaving the RV door wide open with a sheet hanging with weights sewn into the bottom prevents bugs...and lets the pups inside whenever they want.
If you bury the bottom and get creative with a few bags of concrete...you just made a wonderful enclosure you can actually attach a tarp to the top of for shade (it works in the AZ desert...) for under 500 dollars.
Putting a padlock on the enclosure gate keeps the RV every bit as secure as the factory door does. (They are all very easy to break into for a thief...)
Don't give up. You have a good idea there.
BTW, in the summer, some
milk crates placed on the roof and a tarp on top of them makes a hot RV instantly cool.
(You have to keep at least a 12 inch separation between the roof and the tarp. Milk crates work really well.)