Make the amp board out of some kind of plastic. 1/2 inch HDP works very well. Get some 3m super sticky spray in a can at the local hardware. Use carpet to match your boat and it will look really flush.

As for mounting there is a trim rail along the bottom of the hull where the floor meets. This is the same spot your most likely looking at already. As for the top look there the rub rail is screwed into the boat. Not sure on yours but the 06 has a black square looking rail on the inside the factory screw the rub rail into. This is the top mount for your amp. You will only need 2 screws on the top and bottom to make this connection.

Also the screws only need 1/2 inch to bit and that's all you need is bite. No need to screw them in really fare.

If you cant find the upper rail then pull the carpet down from the inside of the hull and you should be able to see where the screws go in.

On my 08 it was just fiberglass. No plastic was there so i mounted some HDP squares tot he inside of the rub rail area and mounted my racks to that.