Well I cant add much more than Artum Snowbird with same truck and camper..
But as to the comment 'they' made, referring to staying back a couple of inches. When loading I stay back a bit, just enough so bumpers are not rubbing while lowering, maybe an inch. When camper is close to floor, then back up to make contact. Otherwise, bumpers wont slide against the coated bed, and Ive ripped them off couple of times. But when all is done, yes camper needs to be against front bulkhead.
On ours the camper bumpers extend 4", so camper can't hit the front bed rail. The SnowRiver bumpers are really that shallow? I also use a spacer due to Ford taillights will touch camper. I ended up removing rubber bumpers, install the spacer (1x4) on camper face then reinstall the bumpers.