Suggestion;

I assume you sanded the plexiglass to provide some tooth for hysol bonding.
100 or lower grit. Another idea is drill holes through the plexiglass in the
bonding area to allow hysol squeeze through and mechanical bonding on the
back side.  I also incidently applied a two bid fiberglass over the
plexiglass bonding area and about 1/12 inches on the fuselage sidethus
capturing the glass.

Hope this helps out.

Bob Smiley
360 94RJ