Speaker wiring and stuff!

[david_12121]

So i went and bought these 2 100w 12" speakers, not knowing that the svx has metal all around the rear speakers...
any other place to mount the 2 or will i end up putting a box in the trunk?
also, the speakers are 8 ohm...i'm pretty sure i can just wire them in but that will end up in them getting half the power (the stereo is a 200w (4X 50w) unit)
can i somehow use both the rear speakers to power the 2 new speakers and get something close to 100w to them both?
any other clever ideas will be very appreciated
(bought the speakers very cheap and don't want to return them)