I keep coming back to these thoughts-

1. I can't trust the diagnosis.
If it *is* correct, I imagine many worse things await whomever opens the motor up. Perhaps 'camshaft' has been mis-translated?

2. re-powering the generator may be easier.
Can the generator be trucked to a city for repairs/overhauls/heart-transplant?

3. discharging your batteries that much, every night, is very bad for them.
The current battery capacity is under-rated for the usage. It would be very wise to increase capacity or cut down the loads.

4. Wow! Beautiful spot.