I have an 06 F-350 SRW SB CC 4WD with a Reese 15K slider that pulls an 06 Sunnybrook weighing 10600 empty. Am getting an 08 Holiday Rambler Presidential Suite SKQ 37, weighing 13300 empty. Does anyone have an opinion on moving up to a 16K or even an 18K Reese? Would the 16 or 18K mount to the rails on the 15K ?
My Opinion only. (I have been wrong before so calculate the answers you receive on this forum and form your own answer).
Of course you will be on the edge of the 15K's capacity, but. I have seen clowns insisting that hitches are rated low and tow 25,000 lbs with the 15K hitch. The hitch then starts failing within weeks of use. When this happens things bend or show signs of problems. My point is if you decide to use the 15K it will most likely show signs of problems well before it needs to be upgraded.
That said there are other thing to be considered. If you have a 15K ProSeries you will notice that it only rocks side to side at the round part that surrounds the king pin hole. This is small movement compaired to 16 and 18K which has a much further travel side to side.
As long as you are not thinking of the Signature series, all Reese hitches fit properly installed rails.