Get a hitch extender/step and a 2" to 1.25" adapter from Harbor Freight (our tray-style rack has an 1.25" mount). Those two pieces extend the bikes out as far as necessary to allow the door to swing open and give us room to climb in. For our arrangement, the step integrated into the extender isn't too far from the ground, but it's a hefty distance up to the camper. I have plans for welding an additional step onto the Harbor Freight unit.
Here is a thread (overly) detailing my truck camper bike rack thought process. You can skip a lot of reading and go straight to my post dated 8-4-'14. There are pics of the Harbor Freight components and our rack. The tray-style racks are quick and easy to load, some have tilt ability for tail-gate access with folding arms for compact storage. The bikes don't bang into each other and they don't swing to and fro.
Bike Rack ThreadHitch Extender/step:
http://www.harborfreight.com/hitch-extender-with-step-97685.html
2" to 1.25" adapter:
http://www.harborfreight.com/2-inch-to-1-1-4-quarter-inch-hitch-adapter-65024.html
Fabricating a step for your existing extender probably wouldn't be difficult, either. Let us know how you do.