I've had Eternabond on my roof seams since my trailer was new and am very glad. On the roof, I did front cap, rear cap and side seams as well as all seams around roof penetrations - like skylights, vents, antennas, refrigerator vent, etc.
There's an argument about voiding the warranty if you do this - but roof maintenance is on the owner, not the company. And if you have a leak beyond six months or so, it is still yours to fix and the damage caused by it. Also, read about how to apply Eternabond as it is requires specific understanding; it will not stretch; the surface has to be clean; it should be pressed down firmly with a roller; once stuck - even slightly - it can not be readjusted.
Another major source of water intrusion is window leaks - not the window itself, but the sealing of the window to the side of the trailer. Many have removed, centered, and resealed windows. At the least, a bead of caulk across the top and down the sides of the window is a good idea. Here is one link to re-sealing windows:
clickyChecking the roof and sides of a trailer for sealing against water every few weeks is a good idea, even if all is Eternabonded - since stuff happens.