I wish mine had all 4 accessible! Mine is a later build but still has half and half. I need to remove my boxes anyways to inspect those spacers (washers) on the bottom to try and sink the box down more.
I wonder if all 4 bolts are needed anyways? I would think just the 2 you can reach from inside the box would be enough to hold the latch closed. Makes for easy adjustments later on.
Take your time eyeballing things if you remove a/some washers. You don't want the RamBox tilting in the space because it needs to have the outboard edge flush with the sheet metal (bottom of door open as you look at it). If it's down tight now, removing the washers will effectively tile the whole box in towards the centerline of the truck and can cause other alignment issues.