Keyswitch Control Board
Here is the layout at the moment, traces are not shown. The left 2/3 of the board is the keyswitch circuit, the upper right corner is the Magura throttle interface. The Magura interface provides variable resistors to adjust the range for the full rotation of the throttle, and it has a connector for remote clamping of the throttle such as used by LVC boards. Shorting the pins will take the throttle to zero.
There is still room for something in the lower right.
Not everything is sized correctly, but most of it is close. Not sure I like those connectors at the top for the keyswitch and throttle, they were library Molex parts. So need to think about what to use there.
The current carrying wires are quad #12 wires which equals a number six. Soldering a number six wire to this board seems unlikely, but a few #12's would be manageable.
The keyswitch needs two contact closures, one for precharge, and a separate one for operate. They must be two separate poles, one operates at pack negative and one at pack positive.