Elise,
Greetings from Iowa.
Like Bob, I had a
U-Haul CT-13 for a number of years, but I think the basic construction & layout is pretty much the same as the Burro.
Assuming that's so.........the wall opposite the door, where the stove sits, has a long flat stretch with no bracing between interior skin & exterior skin, and the skins are less than 1/8" thick; so very loose or floppy or flimsy compared to a fiberglass boat exterior skin. Hopefully yours then is just normal, but was just unfamiliar to the marine repair guy.
I didn't have much trouble with snow piling high on our CT, but on the rare occasions when it did, I 'raked' it off with my shop broom. I have read of people putting a temporary brace or two between roof seam & floor on the inside for the winter, as a 'just in case' measure.
It looked in the one photo that showed the roof that there were a bunch of darker patches on the roof, and maybe a slight dip in the roofline to the rear of the vent. Did a tree limb come down on it? If something like that happened, the roof seam could have flexed & cracked---it's just glued together when they're built. I had to 'saw' a groove through the cracked adhesive for several feet on our CT and then epoxy it back together.... a nuisance job but not that hard. And if the 'trim-lock' type cover over the seam has never been replaced, it's probably due.
And when it's time for re-painting, a lot of people just use a marine primer & enamel, and the 'roll and tip' method......I think this is rolling it on with a
paint roller, and then smoothing it just a bit with the tips of a 'good'
paint brush before the
paint 'sets'.
I painted our CT with automotive enamel & HVLP spray equipment, but only because I did auto-body work at the time. To hire it done, it gets real expensive, quickly.
If it's any encouragement, I have a real long-winded repair thread on our CT on this site.....it was rear-ended by a semi that couldn't quite get stopped in time, when the previous owners still had it. It wouldn't be the same as your own repair needs, but................
https://www.fiberglassrv.com/forums/...t13-66181.html
Best of luck with your Burro,
Gary