I used a larger ac cover and a tube filled with sand. DW sewed the tube and I put the sand in it. See the attached pictures. The tube is long enough to go all the way around.
I got mud daubers in my AC last winter when I was in TX for several months.
This year I went back to the same place with plans to remain stationary the whole time. I got screen material from a hardware store and laid it over the whole AC unit. I fastened it with 3M stucco tape. This lasted the whole time I needed it (over two months) and the tape came off cleanly. (I did not attempt to travel with the screen in place).
The tricky part was that the only screen material I could find was screen door size--long enough but not wide enough. I sewed two pieces together to make what I needed.
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