I would use magnets, not Velcro. How about a screen "curtain? See if these help.
Hi John: Yes, but I'm not sure it would last very long. None-the-less, here's a site that tells you how to do this.
the portable screen that fits my garage door opening is a blessing, we can prep for canning garden produce.
I've never made one myself, but we have this and it's great. l doubt you'll be able to make your own for less than $15 https://www.amazon.com/Homitt-Upgraded-Version-Magnetic-Fiberglass/dp/B06Y2KWM3W/ref=sr_1_7?keywords=magnetic+screen+door&qid=1571278137&sr=8-7