I pulled the inside vent of my 2017 Coleman 300tq Toy Hauler to see if I could discover the size of my roof sheathing. The roof is 3/8" Plywood sheathing. I'm pretty sure the roof trusses are on 16" centers. This sounds like a walk on roof to me?
When I bought the trailer 3 years ago I was told by the salesman it was not but the service manager said it was. To be on the safe side I always treated it like it was not.
But I'm getting ready to install a solar system and it was time to re evaluate.
Probably fine, but it won't hurt anything to use a piece or two of thin plywood to distribute your weight. A little aggravating, but it could ensure you don't put too much pressure in one spot if you have any concern.