Good Morning John: There shouldn't be any issues with your clearances. When looking at hitches, you will find that they are adjustable in height after installation to suit the clearances you want between your bed rail and the forward lower portion of the 5'er surrounding the pin. When shopping for hitches, you may want to use that (how much adjustability the hitch height will have) as one of the determining factors. Most hitches I've looked over are not infinite, but have more than adequate adjustability. Depending on the pin weight, which I didn't look up for the C/3100, will likely determine whether you want air bags on the back axle of your F350. My pin is relatively heavy (unloaded close to 2600 lbs) and I choose to have air bags on the back end. I pull with roughly 12 lbs on each side. The air bags will keep you level, the more "stuff" you put in the 5'er. The clearance between your bed rails and the lower side of the 5th wheel is, as mentioned, a function of where you choose to adjust your hitch height. I'm sure you will enjoy your new setup.