You're going to get some pretty interesting comments and suggestions Bakes unless you tell us a budget, and where you live. I, too, have been looking into a project like this. I currently have an ARE MX shell on my short bed Dodge. I have found it to be a high quality shell, but not big enough to explore out of for my tastes. We spend weeks at the river in July filling our freezer, and that requires a great deal of gear and cooler space. I am thinking that a Wildernest is the answer. However, I am thinking that the tent is pretty lame on the Wildernest, as far as Alaska Outdoors activities are concerned. I think, however, that having a shell that is already cut and hinged is two steps in the right direction. Plus, I can work on this idea in the meantime, while still having a covered load with my current setup. So, I am thinking that either just a 90 degree opening with a better fabric and pole setup, or a vertical lift system, like a Maggiolina would be awesome. Just a crazy idea for now, but I have already begun negotiations on a Wildernest.
I do agree with you on one thing-- that Flippac is too boxy and ugly in my opinion.