Looks great. What program did you use to draw all that? Perhaps you could flush mount the amp(s) with the excess space. Man...it's so nice having extra space.
Not sure what your goals are...but try this: W = 48", H = 21", D = 10" (gross volume ~ 4.5cf) Ports = two 4" diameter ports, 15" long (tuning freq ~ 29.5 - 30Hz)