FYI NS, the TV wall in living room has a full 2x6 on the flat centered on that wall, between the sliding doors floor to ceiling. That would be the same stud in the master bedroom
don't know about the garage. Just get the mount centered within that 5-1/2" and watch screw / lag length. I would say a 46" would work great... its all about the strength of the mount. You might want to consider taking down the TV while traveling. I leave mine up but have cleats on the ceiling and support with straps to take the weight.