I wouldn't put a garden window in there, too wide. Thats a whole heck of alot of glass/weight (double pane glass) roof. It goes to the strength of the vinyl fusion welds. Darn that a heavy window to hang out there. They will probably fix anything that goes wrong over the years, but why would you want them out there fixing all the time! BOW or a BAY is the smart way, close in price also. What about the shelf???

Many years later, we're in the same position. What'd you end up doing? How'd it work for you?