wlwright`

I apologize in advance as I'm not a forum NEWB and expect to be chastised to some extent but if the seniors could provide some guidance, that is very much appreciated!!! LOL... I have searched exhaustively to no avail. I have a late year, non B&O 2023 F150 XLT Supercrew Powerboost with the subwoofer plug in the drivers side rear pillar. I have bought the Forscan module and am willing to enable the rear sub and additional audio mods via software but at this point have not been able to find a harness that will plug into the existing subwoofer plug after enabled that is not a B&O splitter. I do not have interest in wiring into the dash or t-plugging into the mid pillar if a direct connection exists. After this port is enabled is there a harness that will plug into the existing plug and then I can modify the plug wiring (can build my own RCA cable lines) to feed my amp and indirectly to the sub (obviously willing to run electrical through the floor troughs for amp power but want to keep the wiring OEM)? I am somewhat of an audiophile but at the same time a cheap bast*** so would prefer to make my own under-seat boxes as the current audio factory setup is definitely lacking bass and bass expansion. Thank you in advance!!