Yes, you could do that too. Sadly, it may be easier to take out the dash and get the signal from back there.

I had a hell of a time trying to get to the subs under my front seats. I have the multi-contour seats, so IDK if they add difficulty to that. That's one of the reasons I took signal from the amp in the rear. The other being that it was much closer and didn't involve running wires under carpet or trim.