Sounds like a Watson's Street Works battery disconnect solenoid (#L27TM
) might be exactly what you are looking for.
You can trigger it either with a push button or a SPST momentary toggle (or a wireless remote if you want to get fancy). The solenoid draws nothing whether is on or off, so it won't drain your battery. Similar to a latching relay, this is a bi-stable impulse relay. It has an internal ratchet mechanism that holds it on or off. Push the button once and it tuns on...push the button again and it turns off. I bet I've installed 20 of them in the past few years, and I've never had a problem with one yet. They are kind of pricey though.
I could post a wiring diagram for it if you're interested.
Hope this helps....