We did one better - we had a sailmaker cut out the vinyl windows in our pop top and replace it with an ordinary window screen. made a HUGE difference in ventilation. The only problem is when it rains, it pours - if you know what I mean.Alternative poptop cover for warm weather.
Instead of the canvas cover, use a camping mosquito net designed for use over a picnic table or cot.
For a 26 S or D you need to make a hole for the poptop attachment screw to pass through. Just put duct tape on each side of the area and cut a slit.
To hold the bottom down we use a bungee that runs from the rear poptop bolt rope attachments around the outside of the vertical poptop "arms". Two bits of cord hold the front two corners of the bungee "outward" so the bungee actually sits down in the poptop drain channel. Just tuck the netting under this and let the back drape down over the companionway.
We have sailed the bug infested North Channel (and other areas) for over 5 years and enjoyed completely mosquito free slumber. Just be sure to rig it before the bugs come out.
We also use the same bug screen over the canvas cover (for colder or wetter nights) and it keeps the bugs completely out.
For the front hatch we have a piece of screen with Velcro around the edges that attaches to the underside of the hatch opening. Easy to rig, folds for storage and nothing to hit your head on ( like with a framed solution).
The bugs can be kept at bay!
We have even attached another picnic table bug screen the underside of the poptop (just used clothes pegs) and entertained on the cockpit - with the defending roar of a million Mosquitos inches from our ears.
Chris
BTW, my first boat was Catalina Capri 18. After I got married and had a kid, and after he grew up enough to go sailing (about 8 yrs old), we spent ONE night on it and my wife declared we are getting a bigger boat - with a standing room. So we bought Macgregor 25. Now I can't imagine NOT having a pop top...