What sort of truck bed size I need for Gooseneck trailers

Hi Guys,

I have not started yet , planning to get pick-up truck and most definitely will be hooking gooseneck trailer.
My eyes are on RAM 3500 but I am not guided well from the dealer on the best bed size. They say its 8' but keeping in mind Ill be using this truck for day to day city use as well , will I be able to safely hook gooseneck flatbed or any enclosed trailer on fifth wheel with 6'4" bed?
Other than highway runs there will be lot of off road country side and city shipments. Will I be able to make tight uneven turns without busting the back of the truck?

I am just guessing dealer is just trying to get rid of 8' bed I may be wrong!

Thanks You.

 

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