Get yourself one of these: https://www.lowes.com/pd/Kobalt-42-in-Steel-Adjustable-Saw-Horse-1-300-lb/1000105591
One of the settings is just the right size to support the galley flat when the camper is upside down. For $35 it’s worth it to not screw around with making a 26.6875″ (or whatever the manual says) sawhorse out of 2x4s and screws.
