If your trailer came with a ladder, then it is o.k. to walk on the roof. If it did not, then you will need to use a piece of plywood or something to provide support between the braces if you walk on it.
To do inspections without going on the roof, one trick would be to use a selfie stick. Put a ladder up against the side of the trailer, climb up, and put your smartphone on the selfie stick and take videos of the roof. The look at the videos to see if anything needs to be attended to.
2012 Cruiser Sahara 330SS
2015 F250 Super Duty diesel