Sometimes when you go to tackle something like this, you really can't underestimate the need to prototype an idea.
I started with some cardboard and a made prototype pattern that I *thought* would work, but didn't.
The first issue I ran into was that my flexible cardboard prototype -- I'll call it Mark I because that's what Tony Stark does -- seemed to fit.
But when I built it out of 3/4" birch plywood, I ran into an interference on the left side. The angle of the spare tire is different than the angle of the nose. The cardboard was flexible enough that it appeared to work but obviously it didn't work. Next time I think I'll make my prototype out of 1/4" MDF or similar.
I'll call this piece Mark II. Why Mark II? Because II is 1 more than I. I know. You are simply in awe of my prowess.
Mark II suffered from various unforeseen issues. Here is a pic of the first attempt.
1) I covered it in some black auto carpet I had left over from another project. After piddling around with Mark II for a few days, I realized the carpet was going to hold dust and dirt so I decided I didn't like it.
2) I was going to have to make a cut on the left side to clear the side wall of the trunk. The angle of the proposed cut is shown here with tape.
3) When I placed the amp on the board, I didn't think about the 45º angle that the 4 AWG power and ground wires use. I was concerned about vibration and movement loosening these wires over time and I also didn't like the strain placed on the wires with no good way to secure them. I thought about cutting a notch in the board and using some strain relief molding but it didn't seem like a good solution either.
4) The amp board was sitting too high into the trunk which meant it was going to take up more of what little useful space there is in the trunk. I know it's not a terribly useful area but I just didn't like it.
5) As you can see in the picture above, I was attempting to route some of the wiring through the board to keep it clean. This wasn't going to work. The curves are too tight and the combination of techflex and shrink tubing limits the flexibility further. Plus I would've had to offset the board off the tire or the wires underneath the board would rub. Too much hassle. KISS - Keep It Simple, Stupid!
For all these reasons, I went back to the drawing board.