Holdsworth Sleeping Roof Boards

[keynsham1]

I am looking at buying a t25 Holdsworth Vision conversion which is presently only a 2 berth van. The 4 berth version has boards that go across the roof inside to make a sleeping area in the hi-top. Does anyone know if this is just a straight forward job of making some suitable boards or is there more to it. I know 4 berth was an option so I am guessing that the 2 and 4 berth vans are identical?

[normal rules]

Sleeping boards are usually 17mm ply, nothing special, then foam backed carpet, preferably the rot proof type.