I used to carry my bike on my rear 5th wheel ladder and had no problems whatsoever. You can purchase a bike carrier that is especially made for that rear ladder. Today I carry an extra ladder attached to the 5th wheel ladder. The extra ladder is for when I want to put up my awning screen room.
But you can put the bikes on the roof of your truck in a two-step process; first you load the bikes into the bed of your truck, when the truck is unhitched from the 5th wheel, and then from the bed it is easier to lift the bikes onto the roof of the truck. This 2-step process is much easier than going straight from the ground to the roof.
I have a carry-all on the roof of my truck and I first load stuff into the truck bed and then from the bed into the roof top carry-all. I also keep a portable sewer and two gas containers in front of the 5th wheel hitch, and a trunk an 2-generators in the rear of the hitch. All of these items are lower than the truck bed rail and do not interfere with the 5th wheel when towing.
As a full-time RV'er I like my 5th wheel and find it easier towing and backing up than a conventional trailer, plus I have more storage space in my 5th wheel than I did in my previous conventional trailer. It depends on you and your preferences. I have heard from some who say they did not like the steps in a 5th wheel but I had a rather long staircase in my sticks ‘n bricks so a couple of steps in the 5th wheel is no concern for me, but that’s just me.