I had a salvaged door awning that I set up free standing on 4X4s that works well. The comment about making it deeper is a good one. Don't want to stand in the drip line while tending the pit. The thing I did that worked out real well was to mount a 2 foot strip of plastic lattice along the back, then with S hooks I hang my tools, paper towels, racks, etc. Helps keep an unorganized person organized!
Only one critical comment on your proposed setup is ----Your smokers are too clean - get smokin