crash course in 5th wheel hitches?

op wrote:
Some of you are recommending against ANY combination of F-150 and 5th wheel.

I've "done the math", but maybe I'm missing something important. Assuming we can all read the numbers and do simple math, what might I be missing here:
2015 F-150 SuperCrew XLT 4X4 3.5eco Max towing: 11,500 lbs Max payload: 2,020 lbs.
Cougar X-lite 26RLS (one example) Shipping Weight: 6885 CCC: 3070 Hitch weight: 1155

When I do the math, even adding weight for hitch and water and groceries etc. I come out ok.

I see you come from the truck camper area so you should know about not exceeding RAWR/tire load ratings especially with a F150 and passenger car tires (P) which are required by fed regs to have their load capacity derated by dividing 1.1 ....example is say your P tires have a 2250 lb capacity, their now rated at 2045 lb. P tires are only a 4 ply rating and can have just one ply sidewall.

Now lets look at those small 3800 RAWR on the truck. These trucks empty rear axle weight can weigh in the 2300-2400 lb range which leaves 1400-1500 lbs for a payload.
The 2020 payload from Ford is a GVWR payload and is to be spread over the trucks FAWR and RAWR. If you put a 2000 lbs camper in this truck your 500-600 lbs overloaded on the rear axle.

Trailers add little to no weight on a trucks front axle.
The trailer your looking at will have right at a 10000 lb GVWR (6885 dry + 3070 CCC = 9955 GVWR). This trailer may be closer to 8000-8500 lbs road ready. This equates a possible 1600-1700 lb pin weight which will over load your trucks 3800 RAWR.

Your gonna' have to mod the trucks RAWR or look for a trailer with a 900-1100 lb hitch weight.