Bicycles vertically on the Camper Ladder??

Please,before you hang bike(s) on your ladder, consider a front hitch and bike rack. I carried two bicycles on a class C ladder and developed a chronic roof leak. It drove me crazy! I dismounted the ladder, sealed everything imaginable and reinstalled the ladder. A few storms and bingo,the leak would be back, I have been a boater for fifty years and I am quite good at solving leaks. It's a necessity when you have a large,moored sailboat. Camper roofs are flimsy by comparison to boat hulls. They are not intended to bear the weight,sustain the vibration or withstand the sudden shocks incurred when carrying bikes. Additionally, carrying the bikes in the way you suggest only increases those forces.
I'm sure that some people will disagree and say that they've carried their bikes on there ladders over lunar landscapes with no ill affects. Good for them! I,however,know what it's like to suffer those ill affects! Best to avoid them. (Also,easier to load and unload on a horizontal rack).