I once spoke with an installer at JoDi-s in Canton, CT that had installed a remote setup into an early 90s 300D. In this particular case, the guy actually tapped into the glow plug light circuit to know when it was ready to start, and employed some sort of Chrysler brand electro-pneumatic valve to shut the car off, as it's vacuum controlled in your car. He said it was not an inexpensive install, but worked perfectly.

Good luck!

__________________
"If God had meant for us to walk, why did he give us feet that fit car pedals?" Sir Sterling Moss

Michael
2014 E63S Estate
2006 SLK55
1995 E500
1986 Porsche 944 turbo