The ITPS will work with a M10k as a shutdown controller.
The power supply should not be wired directly to the battery of your car. A car produces 13.6-14.3v not 12v. That power supply is designed for 12v. You would need to used the supplied power cord and an inverter. You can still use an ITPS with an inverter and the supplied cords.
Your other option is an opus, the 90w opus is actually pretty small and while it probably won't fit inside that case, it would easily fit nearby.