This picture shows the mounting depth from the sheet metal at the top of the mid-woofer cut-out in the door. It measures about 3.5 inches.
And this is the mounting depth from the bottom of the hole. About 3 inches. Keep in mind that by using the mounting ring I did, I gave myself about another inch of clearance. The JL mid's mounting depth is 2.65 inches, so even without the mounting ring I used I would still have had room.
Here's another look at the cut-out in the door. The black window track on the right side shouldn't get in the way of most speaker magnets. When centered on the cut-out, the JL mid's magnet didn't even come close to it. Plenty of room.
Here's are the holes I used to mount the mid to the door. The red arrows point to holes that were already there and they just happened to line up perfectly with the mid and mounting ring so I used them. I drilled a third hole (yellow arrow) into the door for another. I was not able to use a top (fourth) hole because the size of the cut-out was too large. But with the 3 screws I did use, the mid was securely attached and there was no need for a fourth.
Here's the Sony mid mounted to the door. The silver screws you see are what is holding the speaker to the door. The black screws are what is holding the speaker to the mounting ring. Note the absence of a screw in the uppermost hole.
Here's the finished product. As before, the door had a perfect cubby for the crossover. How cool is that? I'm telling you, that just never happens. Since the Sony amp (or crossover) sends separate wires to the Sony mid and tweeter, I just used them to wire the JL crossover in bi-amp mode sending the tweeter wire to the tweeter input and the mid wire to the mid input on the JL crossover. I then ran wires from the crossover to the JL mid and tweet. Once I get my AudioControl LCQ-1 and use an aftermarket amp I will have to modify the wiring just a bit but that shouldn't be a problem.