Old-Biscut, Forrest River has the 30A fuse in the main fuse panel, not an isolated circuit direct to the battery which would be the correct way. This is one of the things that will be changing on our Surveyor.
Sounds to me like there is a loose connection or pinched wire shorting out when the trailer is shifting in transport. Start at the slide motor and trace the wires back as far as possible, then pull the switch panel off the wall that houses the slide switch and check for loose or bad connections there. I would also pull the front cover off of the main fuse panel and check all the visible connections. If none of this reveals any obvious issues then I would make the 100 mile journey.