I decided to use a slide catch at the back and made a tongue and slot at the front. At the back of the canopy I added a small bit of ply to strengthen the area where the slide catch goes in.
I later added the magnets to hold the canopy down in the middle (mostly for aesthetics since there was a little gap on the edges in the middle of the canopy)

Certainly have no fear that its going to fall off. I used the slide catch since its something I’m used to on other models.
The magnets seem very strong I’m sure that it would have been fine with just those and a tongue.