Ok thinking done. Gonna pop the stock sub back in and leave the car be. Ordered a new head unit, 2 channel amp, front speakers, and an infinity basslink powered sub. Came in under budget of $750 at $660 so I'm happy, and should be easy enough to install everything in an afternoon.
Now to scour around the forum for wire designations so I can just use the stock stuff. I'll be thrilled if I can get away with running minimal wires....