roof strength

my wife and i just returned from a 6 week trip to north and south padre island, texas.  we got along wonderfully with our 2001 3023 pulled by a 2002 toyota tundra.  the entire experience was great and we will be repeating the trip next with reservations already made.  being new to "rving" and staying so near the salt water we noticed most everyone continually washed their rigs to keep the salt water/rust at bay.  we did develope some rust on the front and rear bed supports.  my real question is has anyone experienced getting upon the roof to clean it.  is it stong enough to support ones weight so that it can be adequately cleaned and maintained?  yesterday i was able to get the ladder and do a good job of washing the entire tm and noticed on the roof some fairly serious wear where the coating is worn off exposing metal.  this is a concern.  any ideas?

dennis