Good Morning Philthefrigeman and welcome to TBN. I have a few suggestions.
- keep the hood open on your JD when not in use. I have mice and chipmunks. Neither like the open spaces of an open hood. This seems to be about the best solution - and I've tried most, at least one time. Barn cats are the ultimate answer. If you can keep the coyotes, owls and hawks from eating them.
- your on-board computer for the tractor should have a battery backup to protect the memory. Disconnecting your main starter battery should not affect the computer memory.