There are a few different options here. If want to carry the bikes on the trailer, you could try an over the propane tank rack....check here: Arvika
Looks like they also make a rack for the front of a 5th wheel trailer. These would not work on a V-Nose trailer. The other trailer option would be to carry the bikes inside the trailer. I would not consider carrying the bikes on the back of the trailer, either by a bumper mount or ladder rack a viable option.....there is just too much bouncing around back there, and you can't keep tabs of your bikes.
Personally, I like the bikes on the tow vehicle. That way if we are camping somewhere, the bikes are already mounted if I need to carry my bikes somewhere to a bike path. With a SUV, a roof mount would work. With a truck, in or above the bed for a bumper pull trailer, or an above cab rack if a 5th wheel trailer is being pulled. The last option would be a front receiver hitch mount for either an SUV or truck, but you would have to be sure that the bikes don't block the headlights.
Chap , DW Joy, and Fur Baby Sango
2006 Ford F150 Super Cab 4x4
2008 Surveyor 263