Rich
this isnt the best fitting canopy, and I have done many Loaches in large scale, which have many of the same problems.
Dry fit to the best that you are able. I would liquid glue like Tamiya extra thin, starting at the bottom of the canoopy, and nailing that down first. Don't use the big brush that comes in the bottle, use a very fine 000 brush, on this little canopy a little glue goes a long way. Thin liquid glue will create the bond you need to stick it in place but still be "repositionable" for a minute or two to get it right. Let that set up for a bit, then get the upper half of the canopy locked down with more. You may even need to shim a bit with thin strip stock ( I hae had to shim all of my DML canopies).
Once the bottom and top are secured and dried overnight, begin to work the sides into place and get them secured. For me this has always been the really tough part, but if the botom and tops are correct, the sides will be a fair bit easier to do one at a time.
I find this three step appraoch is far less prone to problems than tring to do it all at once.
Superglue, even with a wax coating on the glass or dipped in future is still prone to fogging in this small scale...I wouldn't try that approach.
HTH
David
Build to please yourself, and don't worry about what others think!
TI 4019 Jolly Roger Squadron, 501st Legion