Maybe...but the other point about flying regional jets is the weight distribution. It has to be right for takeoff, and they have special sensors to tell the flight crew where the weight is located.
I've watched the ground crew load weights into the cargo hold...from a cart labeled "Ballast" - to ensure things were balanced. One trip, flying home from Buffalo, they made an announcement on board at the gate requesting a volunteer from rows 1-5 agree to move to an open seat in the rear of the plane, just until we reached the right altitude, so the weight was correct for takeoff and then he/she could move back to the front.
There may be a reason you won't be able to have your carryon on board with you, and it may have nothing to do with available space.