Hey John - -
I put a 1/8" soft white ribbed rubber seal across the rear-most part of the top of the dash. On the sides of the rear of the dash area, put thicker foam type seals. Under the canopy edges, put a 3/8" foam seal all the way to the rear of the canopy frame. If you work with it a while, you can get it down to near zero air leaks. In Iowa, if you don't seal it, you will freeze for sure.
John Bender