I sympathize having limited access to my GH too and it gets very warm in Summer so auto venting is a must. I was a bit phased by the installation but it worked out quite easy so if you can set one up I recommend it.
Over last Summer they worked quite well for me and I set them both to open at about 20C but still we had temps of 30C plus most days, despite using paint on the glass too, with obvious wilting and stress for plants.
This year I am going to set them for lower temps so heat build up is hopefully less and I also have a louvre in a lower pane with a vent to get some cross draught going. In addition I have curtains ready to go on the sunny side for the worst of the Summer if necessary.
Hopefully some ideas there for you in all that.