The storage area is 11" wide, 10" high, and 36" deep. Note that the doors are only 8" x 8" so this limits the maximum size single item you can get in there.
The poles are too long for the front compartment. I tried to fit them in but they just don't quite fit. I put the side tent (minus the poles) in one of the under bed storage bins and then the poles are in the truck.
We keep the side tent poles at the foot of the mattress. Even if we don't set up the side tent they stay there, out of the way, and don't interfere with the function of the bed.