There are protection resisters (fuses degrade the sound so Wilson doesn't use hem) in the Watt head that you will probably weaken/melt and have to replace depending on how much volume you are playing with. Underneath the Watt and the Puppy on WP7's (I'm sure WP8's are the same) that you remove a ton of Allen head to remove a panel. Inside you will see two binding posts and two resisters attached.. You should measure (you have to remove them) these with a voltmeter after a while to determine if you are degrading the resisters by doing this. Keep in mind that you are putting Sub 100hz bass into the mid range driver... can't say what will happen.
I would NOT RECOMMEND doing this! Call Wilson, I wanted to bi-amp mine this way and they said not to...