If you camper is fiberglass exterior, the manufacturer has block/backing plates where exterior components mount ie ladders, awning, etc. If your camper didn't have an optional ladder you probably don't have anything in the wall to attach the ladder to. If the ladder was optional, you could get the factory ladder and instructions from them on mounting location.
2010 Rockwood 8280WS
2008 F250 CC Lariat SB 6.8L V10
I'm no expert, but I have heard that trailers with ladders were reinforced during construction to accommodate a ladder and those with out ladders were not. Adding a ladder to a trailer would be a tricky move as you will likely not have the reinforcements behind the outer skin to attach it to. Good luck with your quest.
"Sometimes I just sit and think. Sometimes I just sit." "Great minds like a think."
We have a ladder, but it's too small and light weight for me to feel comfortable on it so I just use it to hang my real ladder on.
1* DW "Granny"
1* 2008 Brookside by Sunnybrook 32'
1* 2002 F250 Super Duty 7.3L PSD
Husky 16K hitch, Tekonsha P3,
Firestone Ride Rite Air Springs, Trailair Equa-Flex, Champion C46540
"A bad day camping is better than a good day at work!"
The general rule here is: If it didn't come from the factory with a ladder, your roof is not made for walking on. Before instaling a ladder I would check the schematic on your roof braces to make sure can walk up there. Don't want to end up inside prematurely.
Terry & Marsha
2007 Toyota FJ Cruiser, V-6, 4WD
1987 Sunline Satellite, 20', Reese anti-sway