Originally Posted by Ryan
Which is going to have the most articulation for pulling off road/back woods? Often times I've got my truck in 4 Lo when crawling back into campsites. Friends with 5th wheels have told me that they start rubbing under the front bed area on the truck's bedrails pretty quickly when on mountainy, off-camber ground.
Both the fifth wheel and the gooseneck hitch on the same trailer and on the same jeep trail will have bed to trailer contact at the same place on the road.
So assuming we're discussing only RV trailers, then the type of hitch doesn't matter - provided the 5er hitch has 4-way tilt. You want at least 6" of clearance between the back corner of the bed and the underside of the trailer's overhang if you plan on moderate off-road trails. 8" clearance for relatively rough trails, and 12" or more for "jeep" trails.
On an RV trailer, swapping the kingpin for a gooseneck conversion is useless if you don't increase the clearance between trailer and the top of the bedrail. The only way to increase clearance while maintaining a level trailer is to either lower the tow vehicle or raise the trailer on its' suspension. Or both.
The old saw that gooseneck hitch was better than a 5er for rough terrain dates back to the old days when goosenecks were first available. 5er hitches of those days did not have 4-way tilt, so if the trailer and tow vehicle were at different angles, there was a lot of strain on the frame of the truck and the frame of the hitch. So construction equipment trailers, livestock trailers and utility trailers that are often used in the rough stuff had gooseneck hitches. Plus the front of the gooseneck trailer was designed so the overhang was narrow and wouldn't contact the top of the bedrail on most terrain.
But an RV trailer with 8' or 8.5' wide overhang and a flat nose is going to contact the top of the bedrail on rough terrain if you don't have adequate clearance of 8" to 12" between trailer and bed, regardless of whether your hitch is a gooseneck or 5er hitch. My 5er mashed the top of the bedrail on my pickup when crossing a dip between street and convenience store parking lot
The only reason to replace your kingpin with a gooseneck conversion is if you have several gooseneck trailers and only one fifth wheel trailer. Lots of ranchers around here convert their RV trailers o gooseneck so they can use the same hitch for both types of tailers. But they still cannot drag that RV trailer up a Jeep trail without trailer to bed contact, unless they raise the trailer.