Best shot for solar is a pick the sunniest spot and use some high voltage panels and MPPT controller. Good chance it will fail to maintain the batteries in those conditions. Especially in winter. You can spend hundreds and it may not work.
Partially charged batteries are easy to freeze and get ruined.
I agree with bringing the battery home.
For in season consider an extended run fuel tank to get a 24 hr 100% charge as you leave. But again by the time you haul fuel you may as well haul the batteries back and forth.
Do you have a picture showing some sun?