Just seeking the Specifications for the UPPER BUNK of a Sunline T-1550

[RVNewbie11]

Hello Sunnies,

My 1988 T-1550 didn't come with any mattress or base
for the Upper Bunk and I want to craft something, but don't know
what it is supposed to be like.

I'm wondering if someone can explain what is supposed to be there??

Is there supposed to be Plywood? Thickness? Is is part of the mattress or a separate sheet?

Just a rectangular piece of foam?? How thick? Any "folds" or hinges" in it??? Dimensions??

I want to make what would have been there originally, so it folds up properly and is structurally sound....Presently, one would fall through the two cabinets if they just laid up there! There is nothing there at all right now!

Any chance anyone can explain or take take some pictures...??

Thank you!!!

Mark in Massachusetts

Ps. I weigh about 140. Any Adults every slept up there and lived to tell about it??