The 3M Adhesive remover mentioned above:
Don't know if its the best thing for tape residue or not, and don't know about using it on plexi/canopy but I have used it with no damage to paint and it has removed everything I've asked it to.
I suppose its a matter of opinion but I think it smells awful (maybe a different product) and the smell seems to persist like diesel fuel, doesn't go away, I have to throw the rag outside so I don't have to smell it, but it does work with no damage so far.
Beware: I have used a similar aerosol can adhesive remover called "Aircraft Adhesive Remover" from the auto parts store. I think the can has a lot of blue on it and maybe even a picture of an airplane. It has damaged every paint I have applied it to, some worse than others. Fortunately I've only tried it on junk.
To remove any ambiguity, the product I have used with success is in a red and white can from the auto parts store, is called 3M General Purpose Adhesive Cleaner and it has a product code of 08987