I can totally relate to your question - I had all the same about 3 years ago. I ended up with a 2012 F-150, EB pulling a Wildcat 241RLX 5er that spec'd at 7000# dry with about 1000# on the pin. The F-150 had no problems towing this trailer, even considering it spends about 50% of it's time in the Rockies west of Denver. (I live at 9000')
I've just recently traded for a 2015 F-150, EB and am now in the market for a Rockwood 8289WS 5er, about 8550# dry with #1350 on the pin. With the extra payload I get in the new aluminum body, I have no doubt this combination will work just fine.
Here's more on the current Wildcat: https://smallhomebigyard.wordpress.c...cat-5th-wheel/
And, the 2012 F-150 considerations: https://smallhomebigyard.wordpress.c...0/hitch_notes/
One last item. Those spec sheets you linked to from FR are notoriously out of date and in some cases just plain wrong. Go check out the yellow stickers on an actual unit to make sure you are dealing with "right" numbers.