I'm thinking of something similar. If you live where there are thrift stores like Goodwill or Salvation Army, you can sometimes score a 70's vintage pair of house speakers, and these will go deeper than a Bazooka for the price of replacing the rotted out surrounds of a great set of woofers. You got a Lincoln, I had a Grand Marquis, what I did for subs was there was enough room in the trunk where the spare tire sat to bolt in a piece of oak plywood and mount three subwoofers there. I also got a bulk roll of 4ga wire to run power to the trunk, and to ground the amps to the body. Then ran a battery cable as a body ground under the hood. Used a 140 amp commercial wheel chair lift circuit breaker at the battery. You need some kind of fuse/breaker in case a power wire rubs thru on the frame somewhere. Oh, it ate an alternator once a year too. 1300 watts total.
What I'm planning to try is a panel in back of the seat with 2 subs with a top panel cut to fit inside the wayback, all of this just underneath the roll cover, with 2x3 legs to hold the weight, and just let it seal itself with some thick weatherstrip so it's removable. The idea is a large cabinet for the subs to live in, but keep the weight down. No back so I can stuff stuff inside, and no bottom. Yes, Bazookas are light too. I also have the OE under seat sub. It adds some thump but it's not real bass. I'll use the amp section. The driver is three ohms. I'll have 2 woofers in parallel for 4 ohms. Vintage Jensen woofers from the 60's, very efficient ( while power handling counts, what you need to know is efficiency say 91db/1w/1m and the Fs which is the frequency below which the bass rolls of.) Or refoam those old Advents and just let them slide around in back....it's a station wagon, and it all needs to be out of sight. Unless you live where black out tint is legal. The Haynes manual has a good wiring diagram section.
Check out Parts Express.com for subwoofer kits, amps, and amp wiring kits. They have fast service, and get on the mailing list for closeout deals. No, I don't work for them or have stock shares. They also have a great forum. Check out Midwest Audiofest there too.
And for now I'm keeping the OE radio, not as hifi as my old Clarion, but it has better reception than anything I've ever owned. The sub apparently came with an extension cable that plugged right into the radio and to the main harness, so all the wires for a sub break out there. And WX.