An front underseat sub is an okay route, the issues I see are that if you ever get water in the vehicle, and also fitment. Think of how frequently you put the seat back and if that wiring and box could impact anything.
I would personally consider getting a larger a self powered sub and placing it under the rear seat, with a quick disconnect. You could fit a better sounding sub there (probably a 10" with ease, possibly a 12") and with a quick disconnect could remove easily if you need to remove the rear seat. Under the rear seat is a zipper so you can kind of stuff the sub inside there.
If you go this route, I would recommend a five channel amplifier. You can fine one for a similar price as a 4 channel, and marginally more expensive than a mono amplifier. Relative value for a five channel is there.
Look at the Cerwin Vega B55 bomber as an option. It's $270 and will fit inside your dash, under the steering column. A mono or 4 channel amp is about half the price, so an extra $135 gets you 4 amped channels...
https://www.sonicelectronix.com/item-94247-Cerwin-Vega-B55.html
Now, if you want to go the center console route, that Kicker CompRT is a perfect fit, and the model is dependent on the amplifier's ohm rating (model number ending 671 vs 672). This is an easy install, and I do think you can cut a speaker grill opening in your current center console. Check out the image of the actual center console with grill. Notice there is a square cutout, and three screw holes that connect to the insert. You could do something like this, assuming you have the right tools and can do it.
View attachment 219534