Cutting the catches will work. When cut correctly, raising the lower seat at a 45 degree angle will lift the rear enough to free the back to fold forward. There are a few vids on YouTube that demonstrate this.
Another option is to lift the seat with spacers. This requires no permanent mod to your seat, and will allow the seat to fold forward, and adds room for a sub. (I have not tried or handled these).
Here
The downside to either mod is that if you haul with the lower seats folded up; there is a chance they will not stay in place during braking, or can slam forward and down on a hard brake. Which may or may not be an issue for some. The design on the lower lifting seat cantilevers in such a way as to reduce the actual space behind the seat when actuating motion of the lower seat by more than an inch, so there is less space for storage than what may appear when stationary in the down position. A lot less if you have Etorque, as the 48 volt battery is located behind the driver side rear seat.