Take a 4 f.t piece of 1 1/4 PVC pipe. Cut it into 1 ft. pieces. Put caps on one end. Mix Decon (or what ever kind you want to use) as long as it is the small pieces like treated oats.
Mix the decon with peanut butter, put it into the PVC pipe. Use a broom stick or something that is a bit smaller then the PVC. Push it all the way to the bottom of the PVC.
Clean of the first couple of inch's of the PVC so other critters can not lick off the mixture.
Glue the PVC to a foot long piece of 2X4 and lay them next to the wheels of the RV them put a long nail through the 2X4 into the ground to anchor it. Or use the U shaped fabric spikes and stake the tubes down.
Takes care of the mice before they get into the camper.
Just make sure that the ends of the tube are clean and the tubes anchored so other critters can not lick them or haul them away.