2006 models were before the "walk on roof" designs.
Our 2006 Surveyor had styrofoam sandwiched between sheets of 5/32" luan plywood, so it wasn't walk-on capable.
I used to place some 2' x 4' x 3/8" plywood pieces on the roof to walk on. That worked well.
__________________
Salem 29RKSS Pushing a GMC Sierra 2500HD!
Gotta go campin!