Well this is kind of a non-answer, but it has to be about 8000lbs. Maybe a hair less. I haven't scaled the truck only, but I went across the scales a bunch with a dump trailer tare was always between 12540 and 12660 (probably filled up with fuel when it was on the higher end). The dump trailer was a rental, a brand new 2020 PJ 14k Low-Pro Dump. PJ website estimates the weight at 4250lbs.
Call it 12,600 average tare
Minus my fat *** 230
12,600 - 230 = 12,370
2 little girls, their car seats and all their accoutrement's 150
12,370 - 150 = 12,220
12,220 - 4250 = 7,970
I didnt think the math was going to work there for a second. Anyhow I'm sure if you go down to the dealership and tell them you want to take one across a CAT scale, they'll toss you the keys. I'd bet you're right around 7,700ish.
I know I'm being dense and missing something here, but are you questioning whether the payload number is a reality or what? I mean I looked at the door sticker and figured it should be pretty damn close to that if I weighed it empty and did some math (they don't ever seem to math out perfect). I didn't question it at all to be honest. That payload is what sold me on a new Ford. Very appealing numbers. I just posted in that 2020 payload thread, mine is a SRW 4X4 CCLB LARIAT and it came in just over 4500lbs of payload.