DIY Brenderup Repairs

Been searching a lot on this topic before I commit to buy a 1994 Brenderup Royal TC. It’s a hell of a deal needing some repairs. I want to know if anyone has any experience replacing the side panels up front around (and including) the doors. Current owner has had this trailer since new. Floor was replaced a couple years ago and. When replacing the floor, the dealer used too-short rivets to put the side panels in. They shot right through the panels and are allowing moisture to get in. Long story short, both front side panels and all 3 doors *should be replaced. One side is more in need than the other. Has anyone replaced panels themselves or know how its done? Since I haven’t committed to buy yet, I can’t really get in there and figure it out. Does the roof have to come off, or does the molding come off at the bottom to slide the panels down? It also depends on if I an find the panels or the right material to replace.

I will also be contacting a trailer repair place for an estimate, but would prefer a DIY as I have a posse of auto/marine repairmen available to me…

Thanks!!!