Depending where the car is parked, a battery tender is what you need. But I have to say that if you drove the VW on a regular basis as your daily driver, you would be replacing the battery every two years anyway. This is due to the poor quality of local batteries. In other countries 5 years is the normal life of the battery.
Getting back to the battery tender, even with that you will still need to replace battery every two years but at least upon your return, it will start without jumpers.
Someting like this: https://www.amazon.com/Battery-Tender-021-0128-Maintain-Damaging/dp/B00068XCQU