Never hurts to check with the factory, however, I suspect they will tell you that you don't have the proper
in wall blockers to support a ladder properly. I just checked their site and they don't list a ladder option for any of the Shadow Cruiser line of trailers... If you saw one mounted, it was at the owner's discretion and, unless they peeled the paneling off and installed their own blockers between the aluminum studs and against the inside layer of the filon or fiberglass, they are apt to expose their unit to inside the wall leakage and delamination or cracking allowing water intrusion of the back wall...
If you are willing to take the risk, adding the ladder isn't difficult. I carried a collapsible extension ladder though since I wasn't willing to gamble on a potentially costly repair to the back wall. There are many stories out there of people that act first and think later; at least you are thinking first and will know the dangers going in