Naio what you are describing is a high-amperage latching relay with a push-on, push-off remote control switch.
No question a mechanical operated switch would be the cheapest and most reliable.
There is no question that a mechanical switch is light years more durable than an electrically operated switch with no idle current draw
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But you
will have to buy a new longer cable from someone like genuinedealz.com
Then a 2nd new cable that runs from the new battery disconnect switch to the chassis frame.
Yes this switches battery negative ground not the + side of the battery.
Work out the details as to the optimum place for the switch. Easy access from both inside the coach and outside under the floorboard. From an engine compartment battery I have seen these switches mounted through the floorboard. On the passenger side.
My rationale of using the - ground side for switching is the same as Caterpillar's.
I have seen far too many switching electronic failures when a magnetically controlled solenoid is used. A big block V8 10MT Chevrolet starter can easily draw 280 amperes then slug the system with a humongous voltage spike after the ignition switch is returned to "run" from the "start" position.
http://www.genuinedeals.comMeasure carefully with twine then order custom fit cables from this company.
