There is a thread on spearboard.com that's got a ton of info on Radon boats which are really popular amongst the commercial urchin fleet in Santa Barbara. You may want to browse around there for ideas:
California Dive Boats -- the legend of Radon (pictures) - Spearboard.com - The World's Largest Spearfishing Diving Social Media Forum
I designed and built a little pilothouse for my Avon 5.4mtr which has been great. It's quite easy to do if you want to go stitch-and-glue with cored composite panels.
I know the Anderson and Radon boatyards here in Santa Barbara routinely add pilothouses onto all kinds of boats (Whalers, Pangas....) it may be worthwhile to hit them up. They are all plywood or composite though, not sure if they do Aluminum.
If you find out anything, please let me know. My good buddy's got a Willard 7.3 and he's been thinking the same thing.
here are some photos of my tiny setup:
Spearboard.com - The World's Largest Spearfishing Diving Social Media Forum - View Single Post - California Dive Boats -- the legend of Radon (pictures)