Off the top of my head opinion. If I were going to do this, I would use a Manual Switch, like a knife switch, instead of a Relay type Switch, a solenoid. Why? It will be expensive and hard to find a latching Relay type switch with contacts large enough to reliably carry the high current for the engine starter......and then it's location will be a bigger challenge, as well. Rook
When you get a chance to dance, or sit this one out......I hope you DANCE!
98 National Tradewinds 7370, powered by a 3126B 300HP CAT Turbo, Freightliner XC chassis