Yep, sounds exactly like mine.
I understand completely. I use the cargo space all the time hauling bike stuff around the country for races so the cargo space is a commodity on weekends. I ended up using a 12" enclosure that I can take out when I need the space over base. The system I put in sounds decent enough without the sub. I just take it out when I need the extra space then put it back in when I unload bike stuff.
What I found was, under the center back seat (not the 3rd row) is where there is the most protected space for equipment when all the seats are down. The space under the 2 outside seats goes away when they are down.
Front seats - There is limited room but enough to fit one amp
Middle row seats - See above
3rd row seats - No usable space under them
For a Sub you will definitely need a Line Out Converter LC7i and I am really happy with that choice. There is enough room behind the screen in the dash to velcro or zip tie it down there but it might be a little tight. I put mine under the driver side middle row seat since it's so slim and I wanted it close to my Amps under the middle row center seat.
Doors - 6x8s bolt right in. Super easy but you will need to think about what you want to do with the tweeters in the front doors. The crossover for those is on the lower door speakers so they are wired together and if you don't consider this you will lose those like I did. I'm planning to add small crossovers and new tweeters later. You may also want to consider speaker baffles for the doors since that space is open to the inside of the door panel. I used the foam insert type and just trimmed them down to fit.
The biggest PITA was the door panels. I watched a couple YouTube videos and that helped but still a pain.
Wiring up the Line Out Converter was the most time consuming but the whole project took me about 6 hours. I took my time and stopped/started a couple times to watch videos, read manuals.
Also, if you do an Amp/Sub I would recommend a Sub volume control knob for extra control. I put mine right above where my right leg is when I'm driving.
Hope this helps and good luck
I’m working on a similar project for my wife’s truck which sounds nearly identical to yours. Base model short wheelbase 2017 XLT with factory 4” head unit, no amp, no sub, no nav.
I’ve already ordered 4 new Pioneer 6x8s for the doors and agree that we’ll probably need a mini under dash amp like the 4x45 Alpine to drive them, but I’m struggling with what to do about a sub.
My wife isn’t willing to sacrifice cargo area space with a large cubic or wedge box, so I’m thinking of either of the two options:
1: 8” Kicker HideAway under the front driver’s and/or passenger seat(s). I’m open to running two.
2: acquire an OEM sub enclosure for the left rear wheel well area behind the interior panel and populate it with a higher quality aftermarket 8” sub and 150-250W amp.
The 10” JL stealthbox would be a great option, but at $700 (not including amp) it’s hard to justify.
Thoughts?