Here is what I have:
Onan Remote Start
I believe it will work with about any Onan model, pricey, but it comes in handy. There is also a Y harness that has to be purchased as well.
Bingo
On edit: I have experienced problems in cold temperatures with the propane as well. The only solution that worked for me was to keep a full tank on the auto-switchover side. We do have 40 pound tanks, but it seems the propane problems start when the tank gets less than half full.