Dave, so sorry to hear about your girl. Hope she is doing well now. As far as your canopy, from what little I know, with the squared off back portion, you are going to be generating a huge amount of lift. Only two ways to overcome it, one is to change the shape (which is a huge mystery in and of itself) the other is to have a much stronger latching mechanism. Talking about the force generated by air pressure, consider the emergency exit doors in a 767 aircraft. 34 inches by 52 inches equals 1768 square inches. At 10# air presure diferential from inside to outside, that means there is 17,689# pushing against that door. That is why there is no lock or security device on those emergency exit hatches. You can unlatch but you can't open them.