Cutting factory carpet in two pieces

My rear seats are always out, and I'm thinking of cutting the factory carpet into two pieces under the front seat (so it's not visible). I plan on leaving slits in the rear section around the rear seat mount bolts for easy installation/removal on track days. You could also take this a step further and remove the backing from the front section, which would be left in place all the time.
This should reduce track day carpet weight at least in half, with no apparent drawbacks. Thoughts?
I flipped my back seat down, and cut along that line. That part that goes over the axle/gas tank hump was a little more than 10 lbs. Also cut out a square under each seat. The 4 squares were right at 4 lbs.
But being able to take that back 2/3's out would be even better. And being able to put it back in...
The more I think about the idea, the more I like it. 

