Will keep updated with amp readings.

Putting a switch would be an idea if the fuse wouldn't be controling essential things like cabin lights. Would imply switching them on manually when entering the car, just like home!
Does gm3 also controls interior lights and xenons? If not, means f27 is also connected to something else. That's why a full wiring diagram would be ideal. But no idea where to find it.

I'd say the battery goes at a nln starting point after couple of days. It's my daily so charged mostly every day.