Do yourself a favor, buy a 4x4 rack from ISI it will last you for many many years to come. It is built to last and loading and unloading the bikes is a breeze.
I have their town and country and had George make up a mount for my old Venture trailer.
There is no need to buy a rack for your vehicle and one for the camper.
You could by the 4x4 rack that fits to the rear of your vehicle and you could have him design a mount that would fit on either the front of the camper where the spare wheel is or just in front of it. Although if it was me, I would look at moving the spare to the back. Or you could have him make a mount to fit the bikes to the rear of the camper.
When you want to use the camper, simply remove the rack from the standard hitch mount and attach it to the camper mount.
The design of the ISI is such that the rack is angled up behind the vehicle, This helps to cut down on the total overhang length but also keeps your bikes well up out of the way from rocks etc. You can travel along rough roads without the worry of the bikes hitting the ground.
The bikes are very easy to load, the front and rear wheels sit in a cradle and a center post locks them in place with padded hooks, each bike is separate and do not rub against each other.
The rack is also hinged, if you have it on the rear of the vehicle it swings down to allow access to the vehicle without having to remove the bikes from the rack.
More info here,
http://www.isi-carriers.com/index.html click on the Adventures tab to the left, this will help to give you ideas.
if you see a Hyundai IX35 and a white Venture trailer this is ours

George is excellent and nothing is too much trouble, give him a call and expalin what you want and he will work with you, to come up with a deign that suites your needs.