That seems like a good idea... I'd also consider using 1/8" plywood that would be absorbent enough for resin to actually bond to.Jack you might consider a reinforcement bar across the roof, inside, from left to right. I have a glass replacement top on my 45 and it flexed pretty good at speed. During the rebuild an inch wide strip of steel fixed the issue.
Alternatively, 1/16" aluminum scuffed up, coated in resin, and secured in place. A few layers of glass on both sides, rolled over with some resin, covered with PVA plastic, and then squeegee out the excess resin. Once it cures, coat both sides with some gel coat and/or resin mixed with micro-balloon to fill in the imperfections. Once it's all cured, some body filler, paint, and call it a day.