So you play “every other weekend” log in every weekend.
You don’t need to spend much time on those off weeks, just log in and it’ll refresh the decay timer.
Or if that is too much trouble, consider the Dedicated server launcher
Set up a server, turn off decay. Now you can play however you like, as often as you like.
Just one of you will need to host the server, I have an older PC running my private server on my LAN.