That's an interesting idea and I don't see why you couldn't. I'm sure you could build a frame (wood properly sealed?) to match the contours of the original top and make the top of it out of Lexan, plexiglass or something similar.
As for getting additional height, I have an '86 Cadet
too. It's currently a "project". I have all of the original top parts except for the mesh but I plan to secure the font leading edge of the top to the trailer with a hurricane hinge or something similar so that I can lift the rear of the top up to about 12". So rather than going straight up 4" or so only the back will lift but much higher. I'll have to make my own mesh (don't have one any way) and gas struts will help to lift it and also keep it up. This will allow in a lot more light
and air. I have a tear drop trailer and the lid (much bigger!) lifts this way.
I like how you've done your front window. Do you have pics of it?