Well at least you have a clue about how heavy your trailer and van are. Some drive on clueless. And with 10 kids, I was suspecting that the 15 passenger van with a 1,000 pound hitch weight might be well overloaded.
Here is the bike rack system for the trailer hitch - over the propane tanks.
http://www.etrailer.com/Trailer-Cargo-Control/Stromberg-Carlson/CC-275.htmlYou can click on bike racks to see what they offer, as well as roof mounted bike racks. You might try putting 4 on the front of the van (front hitch) and 4 over the propane tanks. Then put the remaining inside the RV?
Good luck!
Fred.