Older Front Living Fifth Wheel

I just upgraded from an 03 F250 to a 21 GMC 3500 simply because the 03 did not have the payload to carry the 5th wheel we wanted. From what I have found most FL units are going to be on the larger size. Having the separate room adds length as opposed to having the living and kitchen combined into one large area. I just bought a Durango Gold 387FL by KZ. Its GVWR is just over 16K Currently I am within my cargo capacity but if I maxed out the trailer my truck would be over.