The style of hitch is not going to make a difference in wind resistance from the camper. I just bought a 5th wheel camper but have yet to pick it up. I settled on the B&W Turnover Ball gooseneck hitch with the Companion 5th wheel adapter. This is by no means the cheapest route to go, but it appears to be the most sturdy and versatile setup of it's nature.
After several weeks of research I could not find a single bad comment anywhere regarding the Companion adapter. If you adapt your 5th wheel trailer to fit a gooseneck hitch in the truck, the trailer will be allowed to twist on uneven ground and could contact the bed of your truck.
The full B&W setup cost me $995 delivered to my door. It's not cheap, but I guarantee you that I now have all the benefits of a 5th wheel hitch along with all the strength of the gooseneck hitch. I won't have any obstructions in my bed on a daily basis nor will I need to worry about a flimsy gooseneck adapter when I tow a 16,000 lb trailer.
If you read the entire thread that was linked previously, you will see that there are many options to do what you want to do. The prices range from a few hundred to a few thousand dollars. I should have my B&W installed by Thursday and will pick the camper up on Monday. I will be able to give you more details at that time.