I have a friend who lives in a permanently set up bus who painted his roof with Isuladd paint and claims good results see link. http://insuladd.com.au
There are also two other companies who do roof paints...... Thermoshield and Barrier paints, you could Google both do thermal insulating paints and should do the job.
Cheers
Trevor
-- Edited by Yuglamron on Sunday 16th of December 2012 02:52:28 PM
Hi Chrisnchris ,not sure where your based, but if you can visit a local panel beaters and ask what they'd use it might put you on the right track, I'd ask a few so you get a good idea what is around, re:what to pre clean it with, right temp to spray etc.