This has been a frequent question on Honda Element forums. The E has enough space for sleeping (6' on the floor with the seats up, 8' with all seats laid flat), and a clam shell tailgate. It is possible to exit through the side doors, but some find it awkward
The simplest approach is to lay a sock over the latching mechanism. The upper tailgate can close but not latch. Probably won't work with the barn doors.
Another is to drill a 1" hole in the plastic liner directly over the locking mechanism, and use an extended finger to move the lever. That, obviously, depends on finding the mechanism, and the depth of space there.
Others have rigged cable releases, using a bike cable, chock cable, etc, and locating the pull knob at some convenient point, usually on plastic trim near the glass.
The next step is to install a solenoid and cable release.