This whole thread hurts my head. Sell the wheels and buy wheels that fit your Subaru (the right way). Wheel spacers (if not done right) are a really bad idea. I'm about 75% sure at some point, one or more of your wheels will fall off, or you will damage something.
Only way I would run anything like that would be if I bought the correct (hubcentric) spacers (10-15mm max). No changing of bolt patterns, or double bolting needed. One you put those adapters on, then mount the wheels, you will have to pull off and re-torque the adapter to the hub, and then torque the wheels to the adapter a few time. Way too many extra parts for me.
Not to mention you are talking about putting on offset tires too? Ugh... Not a good idea for an AWD Subaru.