I guess I'm not really understanding the problem. Pictures? Fuel lines are easy to move. Jacks should clear regardless. Worst case, rear of the camper (anything past the 8' mark) might have a section/part that is lower (i.e. our wings hang down about 1/2" lower than the bottom of the camper). Just put the camper on a mat, or plywood, etc, to raise it up a bit.
I'm not following why the narrowing at the rear? Deck at the back would work great..we use to have a pull out deck that stored under part of the flatbed on another truck.