I'm all done in the fuselage, except for connecting seat belts, so might as well put in the rear window.
It was difficult taking off the celephane. Next time I will be more careful to avoid scratches in the plexiglass.
WD-40 removes tape goo without huring the plexiglass. Not suppose to use solvents like acetone nor MEK. WD40 does a great job of cleaning of sticky goo without scratching.
For a sealer I decided to use clear Dynaflex2 because it is flexible and dries clear. And it is weather proof.
I applied tape around he areas where I put the sealer so that it wouldn't squeeze out and get on the plexiglass. But it did and WD40 cleaned it off fine.