[busterbrown]

Fully walkable? I doubt that. Did it come with a permanently mounted roof ladder? If not, your class of RV is considered an ultra light (as is my Bullet). Your roof's decking is extremely thin (probably 1/4" OSB) and will not support excessive weight between the rafters. Weight reduction is the primary driver for RV manufacturers with their ultra light lineups. Take off one of the vent garnishes and you can see exactly what I mean.

The best option for those who own ultra lights like ours is to buy some 2" thick polystyrene foam board and cut several pieces (2'x4') that can be used to distribute your weight across two rafters. It's worked well for me and for many others on these forums. The foam board is non-abrasive and will not harm your TPO roof.