I was able to finish framing for the front facing window (and with that finish the roof spars). I bought this 15 x 18 crank out window:
http://www.amazon.com/gp/product/B01347 ... DV687MEABS
I bought it not knowing if I would be able to use it, but it looks like it will work for my purposes. the installed crank only allows the window to open about 7 inches. see pics: I was able to remove the crank push out arms from the window frame channel. this just required a push or two with a flathead screw driver to remove a plastic spacer. Once the crank arm mechanism is removed from the window frame channel the window can be pushed out either fully (to a 90 degree angle to the frame) or be taken out completely (which is what i did while getting the framing done).
because of the curvature of the front end I had to cut 5 inches down into the front bulkhead wall to assure that I had enough flat surface for the window. from that cutout i completed the framing using 1x2 (across top and as a final spar since no screws go into the top or bottom of the window, there is also no internal trim ring) and 2x2 for the side framing since the screws are on the sides of the window. it is seated in the wall cut out which is 3/4 ply and 1x2 frame.
I bought this window air conditioner http://www.homedepot.com/p/Frigidaire-5 ... /206734522
it is 16 wide by 12 tall, and fits through the fully opened window. so when not using the a/c I will have a functional window (the crank bars are easily reinserted back into the window frame channel).