Donna, the supports are not screwed into the walls, they are a tight fit in the gap between the bench seat and the wall. An Egg not having a gap to jam the support into might be an issue as you're right, the cushions alone wouldnt be enough. I saw a post on here where somebody had built a bunk over the main bed in their Egg. They attatched the front legs to the cabinetry (closet, kitchen) and the rear legs it seems like he may have velcroed them to the Fiberglass? That part I'm not sure about he didnt screw the support into the Glass I remember that. Maybe it was enough that the front legs were attached so the rear ones just sat up against the corners. For the life of me I cant find that mod.
Yes Nancy, the T@b wheels are further back and another option to lighten the bunk would be to use webbing like on lawn chairs to support a foam mattress instead of the plywood platform. The Black bracket you see is the hinge system to raise and lower the seatback. When all the seats are in the up position you have a "U" shaped sitting/dining area, you lay the seatback down to get the 73 X70 bed. So one of the support legs is between the seat bracket and the wall. Everything is pressure fit and very stable from what the orginal modder (is that a word?????) said. If you were worried about tipping you could leave the bunk pieces on the main bed till you arrived at your campsite and then assemble.
In these pix the table is not installed, It goes where you see all the open floor space. Then the side cushions slide down to cover it just like the Eggs.
The platform base is attatched to the legs with Industrial Velcro so it can be removed/installed in seperate pieces. You probably could use some sort of latch system as well instead of Velcro.
Melissa in Florida
1999 Toyota Sienna XLE