I used two vertical boards outside that use bolts to hold the frame in place. Really I just use those to keep it steady when Im putting the AC in place, after that the weight of the AC holds everything in place. So to remove the frame I take the 4 bolts out and then it comes right off. Let me know if want some additional pictures.
One thing worth noting is I used pipe insulation on the bottom of the frame, where it rests on the wood inside the camper. This mostly eliminated any vibration/noise from the compressor.