LOC or Wire Harness Adapter for non-JBL

Im looking to add a little bass to my non JBL '17 TRD Sport. I plan on dropping a powered enclosed subwoofer under the drivers seat, or behind my back seats (double cab). I would love to have a clean install with a harness adapter from the back of my head unit, instead of having to tap into my door speaker wires and figuring out where to get the remote wire from.

Is there anywhere that sells a harness adapter for the back of a non-JBL head unit?

If not, has anyone had any experience installing a LOC / remote turn on in?

For the record, Im thinking of the Kenwood-KSC-SW11:
https://smile.amazon.com/Kenwood-KSC-SW11-Compact-Enclosed-Subwoofer/dp/B00BO8O9XQ/

Thanks