A few weeks ago I showed this photo of a curved fixture I built to test installing these flat RV windows in the curved JK hardtop. The curve of this fixture matches the curve of the factory hardtop mounting surface. The window in this photo is just setting in place, it hasn't been fastened in yet, but you can see how there's a gap between the corners of the window and the mounting surface. If you fasten the window in place and attempt to bring those corners down to the hardtop, the slider will bind.
To make the test a better simulation of the hardtop, the other day I painted the fixture and added trim around the window mounting surface so it looks a little more like the real hardtop.
In this next photo, the window is secured in place with a prototype of the retrofit kit, which adapts the flat window to the curved mounting surface.
Here's a video of the window in operation, it slides very smoothly:
This is a proof-of-concept test for the retrofit kit concept, and as such, it does prove that the concept is practical. With this kit, pretty much any standard RV-style windows could be installed in the JK factory hardtop. If this kit were to be manufactured, there are a few details to work out, but one of the window companies I've been talking to is interested in working on those details with me.