I've been doing Apiguard Gel in the summers and OAV in the winter for several years now with excellent results. Like you, I do a half dose each time due to the hot Texas summers here. I use a 1X4 homemade shim on top and put the gel on top. I close off the screen bottom boards and put on robbing screens on the entrance. Works good for me.
Good luck,
Dave
Good luck,
Dave