Hi TJ, I too have nearly completed the 34" version bought at Warwick last year and have also followed Les's build (Tailuk) which was a big help, didn't really look at the instructions. I also contacted him re the window frames but Les has the skill and opportunity to laser cut them, an important point he quite rightly made is they are nearly all different sizes.
I hand cut mine out of plastic card, 2 each of 11 different sizes! I used the laser cut wooden pieces (that are removed from the openings) as templates for the 3mm acrylic windows I used. I temporarily stuck the acrylic to either side of the templates using light tack double sided tape and cut around the peripheries with a roller guided router cutter, was pleased as they fitted in a treat. I used waterproof double sided tape stuck to the back of the frames, removed the excess overlaps with a scalpel, removed the backing paper, lined up and stuck the acrylics to the frames and pushed them into the apertures so that the overlap of the frame stuck to the sides of the cabin, two birds with one stone so as to speak with no mess, no glue. Will happily post a pic or two if it will help.
Oh by the way, you'll also find there is no provision for cabin flooring above the motor compartment, not difficult to overcome but it's a bit of surprising omission I think nonetheless.
Anyway good luck and enjoy the build, kind regards, Tony.