I guess you don't have a usable basement?

My house is a hair over 1000 sq. ft with a full basement, subtract out the mechanical stuff down there and I've probably got about 900 sq ft. for pins, whatever.

Can you make part of the garage 'part of the house'? i.e. put up a wall and extend your heating/cooling out to it? (2 car garage to 1 car).

Likely you sprayed too thick of a coat and it's lifting where the original ink had weak adhesion.... as it's drying it's shrinking slightly and that's what's pulling up the ink.

The key to triple thicking is thin coats to start and after the triple thick has sealed the glass, then the thick coat if you feel it needs it. Because of the risk of what's happening to yours, I no longer triple thick backglasses that are in decent shape to start with.