FYI, the thought that a load range E tire is rougher/harsher is a myth.
If you are truly wanting/needing a M+S tire, that tells me that you *might* end up off-road. The greater capacity of an E-rated tire will support the weight of your truck better and handle "difficult" situations much better. And if you ever load the truck (to tow or load the bed), the P tire can become dangerous.
When I got my '13 I swapped out for E rated tires after about 900 miles. The ride was more controlled, but definitely harsher or rougher. Rides like a Lincoln town car. The harsher ride comes from how much air one runs in the tires, not the tire itself.
Hopefully this will open some doors for you as far as choices. FWIW, even when I sold tires I was never a fan of BFG. There are better tires out there. The Toyos are awesome tires. The MT get real noisy though.
2013 F150 FX4 EcoBoost
Sterling Gray S-Crew, 402A Pkg, Bilstein 5100 1.5" Level, 275/70R18 BS Revo IIs