Well filling in the blanks, I lift ours by 1st letting all the air out of bags. Then I lower rear jacks to contact ground. Note level bubbles, double check e brake and raise the front until bubble shows nose high, then alternating front to back until bed no longer rising, quick peek under rear to ensure its clear, reach in and unplug umbilical, then roll the truck out a few inches. Raise a bit more then pull truck out.
Want to minimize the travel of rubber stops against front of bed. I think on ours running up the front till its nose high its also moving it away. I can 'hear' when it really tight-sometimes Ill stop, depress the brake pedal-release the ebrake- stab the clutch then let off brake, reset ebrake.
Ive ripped ours off quite a few times in the past. I mounted a 1x4 across the front of camper (needed more tail light clearance), the extra material and 1/2" longer lag bolts seems to have stopped that. That and I slip a piece of cardboard in-between as our bed coating is so rough-no way the rubber stops can slide. Being 4" tall on a 2" wide base laid horizontal even with bolts countersunk, lot of leverage.
The carpeted lumber a good idea. The bumpers only are only there to act as spacers-so anything would work. I was always going to have a piece of stainless sheet bent & plasma cut-for a smooth area and to help with the point loading/bending of bulkhead & have under mat so lead of box resting on it.