I suppose you could use magnets. You'll have to do some trial and error testing though. You would want the magnets strong enough to keep the screen closed but not so strong so that the screen door would not follow the main entrance door when it is opened.
BTW, yes it is somewhat of a pain. I'll have to think about this for out coach.
Paul, Kathy, and Tux a 4 month Mini Schnauzer
2014 Tiffin Phaeton 42 LH, 2013 Honda CRV
"When the time comes to look back, make sure you'll like what you see"