Sounds like a good plan. Figure a couple hundred bucks for wiring, fuses, etc.
Only thing I might suggest is getting a bigger amp for the cockpit speakers/sub. Can get a 5 or 6 channel for similar $ to the 3 channel.
'06 X2 MCX
"I understand why some people may not want to do this the way I have recommended but I can't understand the death grip some people have on a toilet plunger with a hose fitting." -JimN