125 g in wall aquarium

I am looking at building a 125 g in wall aquarium. The wall I am placing it in has a metal support post that means that the tank will be recessed about four inches (2 x 4 + drywall) and the display side will only show about 5.5 feet of the 6 foot tank. Since I do not want to drill the tank I was thinking of building an integrated sump on the one end with a compartment for mechanical filtration, another for the skimmer, space for a heater and a compartment for the return pump.

Does anyone have experience with doing this on this size of tank? Any advice?