Well, my patience expired and I made my own solution. Here's my audio setup and take on a sub enclosure:
I've got a JL Audio MX600/3 amp mounted under my dash in front of the steering wheel. It's a spendy amp, but it has a small footprint and is, essentially, two amps in one. It's got 2 channels for my tower speakers and a subwoofer channel with dedicated sub inputs and tuning controls.
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For simplicity, here are Amazon links to all the products I'm using for my audio system as well as some info on my sub box I made. However, I'd recommend reaching out to Chuck Holey with Trailstar Audio to see what he can do on pricing. He can probably save you some money if you buy through him as a package.
Head Unit:
https://amazon.com/Rockford-Fosgate-PMX-2-Compact-Receiver/dp/B0108LNLBK/ref=sr_1_2?crid=21XPSXL08JD8T&keywords=rockford+fosgate+pmx-2&qid=1576685144&sprefix=rockford+fosgate+pmx,aps,161&sr=8-2
Head Unit Mounting Plate:
PBR Products fits Honda Talon 1000 3
Tower Speakers (these things are unbelievable for as inexpensive as they are):
Amazon.com
Amp:
https://www.amazon.com/JL-Audio-MX600-3-Channel-PowerSport/dp/B07CB25T1D/ref=sr_1_2?crid=WWZ0GD4TQTRP&keywords=jl+audio+mx600/3&qid=1576684928&sprefix=jl+mx600,aps,163&sr=8-2
Subwoofer:
Amazon.com
Subwoofer Enclosure - It's a 10" down-fire box that I custom made out of 3/4" MDF using pocket hole joinery and wood glue. It's been sprayed with Rustoleum truck bed liner for a finish and is sized to work so that I can run my soft cargo bag on top of it and also use the JEI Bed Extender to haul my cooler around. If anyone wants specifics on the sub box I have a detailed plan with parts and a cut list I can share.
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