Order guide, which is online usually if you search for it but isn't generally supposed to be public. Easier, you just do a build/price on the website, print it, and send it to the places doing the invoice + pricing for a quote. They will just send you a copy of the order which includes both invoice and MSRP.
There's no set percentage, it will vary based on option packages, manufacturer, etc.
I don't have MSRP listed but it was about $80k IIRC, but you end up with something like this with the option codes you want. This is a 2023 Tremor I spec'd out and sent to 3 places that do invoice + and then the total cost with their doc fees before I bought my Power Wagon instead:
2023 F-150 Tremor SuperCrew® 4x4 – 5.5' Box 145" W1E
3.5L V6 EcoBoost® with Auto Start-Stop Technology 998
High package 402A
Auto Start-Stop Removal 52X
Front-Axle w/Torsen® Differential 61T
Partitioned lockable fold-flat storage 60P
Twin Panel Moonroof 43V
$65,393.41
$64,970 – Chapman
$65,112 – Granger
$65,700 - Laura