Let wood screws do the clamping
Here's a way to cut down on the clamping time and number of clamps needed to glue up the sides (A/B/D and M/N/P). After clamping up the first side and checking for square, drill a screw hole centered in each half-lap joint. Then drive screws, as shown at left, remove the clamps, and set the assembly aside. Now your clamps and bench space are free for assembling the next side.