I don't have a CLASS-C, but my Outback came from the factory with a small hitch already welded to the frame. (I forget the size, it's the small one).
One of the first things I did when we got the camper was to get a carrier for it. It does not have a ramp for an automated scooter, instead we got the sides on it to make a cage.
The first thing I noticed however, was all the wiggle it had. With the single point of contact (the receiver) that came factory installed on the camper. However, it had so much wiggle in it, the ends could move a good 6-9 inches up and down. This was not acceptable.
So I ended up bolting a couple of 2x4's to each side (on the bottom) of the carrier. The bottom of the carrier matched to the top of the square bumper tube just perfect if I used my old bumper mounted square hitch receiver from my previous camper. By making the 2x4 an extension to reach the top of the bumper on both ends, the entire unit became incredibly stable. We've used the carrier many times. The weight of the carrier is actually on the hitch. The 2 side 2x4's are just for balance. I'm sure they carry some weight when it wants to wiggle, but so far, after 18 months of owning this camper, it's worked pretty good.
By the way, I got the carrier at TSC (Tractor Supply Company).
EDIT? What do I carry in those two tubs? The long one are the sewer hoses ... I have a bunch of them in there for just about any configuration. The short one holds the water hoses. The carrier is perfect if we have to pack up after a rain. Just roll the rug and let it drip there, keeps the bed of the truck clean and dry and don't have to store it in the trailer either (if it's wet).