Thinking about mounting the MSD box behind the fender. There appears to be plenty of room and there are no user adjustments for it. I've used them for years and have never had a problem with them. I've run out of room in the engine bay. The tape is there just for mock up.
There's a plastic shield that should go in front. I've seen an Infinity Box installed there. You could make some sort of a bracket that would mount it with easily accessible bolts. Then just pull the shield in case your spark disappears. You can even put wires through the cowl hat or antenna wire grommet to feed power.
I originally had mine in the glovebox, I thought it was causing interference so I went through the butt pain of moving it to the fender well as well. Turned out not to be interference but I still like the location. I did use shielded wires for the triggers though to be safe. The metal splash shield does a good job of keeping it clean and water out, not perfect but good enough and the box is supposed to be able to withstand elements. She’s seen many a track day as well and I’ve never had an issue, easy to get to it need be, took me 5 mins to pop the shield off to take these for you
Made it over to the shop. With the MSD mounted where it is, the wires make it to the coil on the front of the radiator support, the power to the MSD (big red) makes it to the battery side of the starter solenoid and the red wire that goes to the ignition switch makes it to the ignition switch on my control panel (beside the diver seat).
I don't have the momentary switch wire hooked up to the starter solenoid yet.
That place gives me the willies, don't think I could do it. Does not look like a place electronics belong, especially with exposed connections e.g. the chip. I tucked mine next to the radiator on the support on the drivers side under the regulator 23 years ago. Painted it satin black, sanded the fins though and taped off the MSD sticker. Coil is on the block, again painted satin black. It disappears in that corner there and has been happy there...
I’ve have two Mustangs, one for 18 years and one for 6, both have had MSD boxes the entire time and anytime I thought it was the box it turned out it was something else or wiring. Just my experience and I’ve found that even a lot of my friends that suspected the box turned out to be something else and MSD themselves have always said the same, just my take though. I have zero issues having it there, it has the slash shield to protect it and it’s easy to get in and out with the rubber mounts and weatherpack connectors I put in. May not be for everyone but in my case I wanted no wiring or external stuff visible in my engine bay unless you were looking for it so it wasn’t option.
Mustangs to Fear has a Box for mounting ECU's in that location. you cut out a section and weld in the box so its open to the inside of the car. You could adapt the idea for the MSD module if you want to put the work in.