Started out with a 24"x 30" frame-less window I bought on Ebay for $44. It came with inside trim and a screen. and was made for a 1 x 1/2 wall thickness. (Was quoted $400 from 2 RV window co's).

I cut the frame, screen and trim ring down to 24"x 8 3/4"" This size was so it would fit between the horizontal wood braces that go across the back, and also small enough so the curve would not be an issue. 

And then ordered a piece of smoked,tempered glass to fit the new window size from my local glass shop for $48, I had to break the old window to get the hinge and roller slide bracket off, and then I used windshield mastic to apply them to the new window.

I removed the trim piece that goes between the ceiling and back wall, and pulled the wall panel back a little to see how much room there was between the horizontal braces and make sure there were no wires. I then made a template that matched the window cut out size and cut the inside with a utility knife. I then transferred the template to the outside by drilling holes to line the same template up. 

Here I forgot take a picture of the outside work, but I made the cutout with a 4" angle grinder with a tile blade on it. And turns out I had to shave a portion of each brace to get the window to slide in. I added a brace under the lower piece to make up for this, (window should have been 8" tall). And seeing that the fiberglass was just floating off the horizontal braces I added glue in the gap before we put the window in.

 We put a heavy bead of silicone on the window flange and put it in place and Rick pinched  the window frame and trim ring together while I snugged it up by putting 18 screws through the trim ring into the window frame. This pinched up the window real tight to the inside and outside walls and we got good silicone squeeze out from under the window flange all the way around. 

It took about 2 hours to install with much pre planning, and prep work. And I think it worked out well, and should let in a little light and give a good air draw to get rid of moisture in the bathroom.

 

Life is good, John