2020 underseat subwoofer+speaker amp stock head unit questions

Hey yall,
so in my 2008 access cab i had a powered sub, loved it.
made it sound full not over powering def wanna accomplish the same goal.
but in my second gen i put it behind the seat, and for my 2020 DC i wanna put it under the passenger seat.

has anyone done this or accomplished this goal in a 3rd gen? advice?
i really dont want to lose the back seat storage as i overland quite a bit and have it filled.

I yielded no results in my forum searches so if you have a referral to a post please send it my way ive spent days trying to find the right thing.

i currently have upgraded all speakers to kickers including the tweeters it sounds ground but it peaks and im having none of that.

looking for a good 4 channel as well, but i already have some in mind.
if you have an opinion lemme hear it always up for suggestions

my question for that is, has anyone installed that similar set up into a stock head unit?
how did you accomplish it with what adapters for two separate amps with the stock head unit not having rca inputs?

also knowing im going to eventually upgrade the head unit likely to the halo.
did that make a difference in your set up preference?

lemme hear it nerds