1.5" clearance ain't bad.
My set has only 1" and the wider end has to come with 0 clearance on side of gate opening.
On front I put 2x6 board where the camper front would rest and attached 4x4 blocks with taper who would push the camper into center.
That said for 1" difference you can lower the side you want to move into a bit down and with some hand push that should do the trick.
That said, I was loading my camper for 2 years using side mirrors, only to discover for season 3 that my 360 cameras have trailer mode, who combines pictures from both side mirrors side by side, so you don't have the parallax error the mirrors have.