Putting all that weight on your mobilehome roof? Not to mention permits etcetera, it's a bad idea.
You're much better off using an EPDM rubber coating. You can get it in 45mil thick sheets, but the best way is to get it in liquid form and paint it on.
EPDM rubber is way better than the acrylic latex roof coatings you get from Home Depot and the like. It's lightweight, flexible, insulating, lasts practically forever, you don't need a permit, and it's a breeze to use, you're done in just an hour or two depending on the size of the roof.
These guys have info about it:
http://www.liquid-roof.com/ (nope, I don't know anyone at that company, I've just used their product and really liked it)
Hope that helps you out.
ChrisR
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