Mine comes out and leaves a smooth bed. Mine is a B&W 5th wheel companion, and when you pull the 5th wheel hitch out you can drop in a goose neck if desired.
I had the rail system and always had to lay 2x4's in the bed when using the slide in camper, Flat bed is the only way to go for me
Allen
http://www.pplmotorhomes.com/parts/r...FRMUagodr3kq-g