I’ve been looking at the options too. We were once burgled in our previous Beach. We were sleeping upstairs and thieves cut through the mosquito mesh on the sliding windows and stole lots of bags and gear. It has made us a bit nervous. We now have a Caravelle, so sleep downstairs (well, there is only a downstairs!). There are lots of magnetic options for the cab windows but I would ideally have liked something more secure. I’m clearly paranoid now. There are quite a few recommendations in other posts for wind deflectors that allow you to lower the window a couple of inches and still maintain security. However, they only really create enough ventilation if you have a throughput of air with a tailgate device that holds the tailgate ajar.
So, my current preference would be magnetic midge screens at the front with the passenger window about half way and the driver’s side (where the locking button is accessible) less open.
Still keen to hear recommendations.