Re: Moving old, but occupied hives
I think your plan will work well. I moved a very full-of-bees hive this spring to a location 100 miles away and used the technique you are describing, except that for the top plywood I cut a large opening and covered it with window screen for some ventilation. The top plywood was held on with 3/4" screws and the bottom plywood with bungee cords. I have a little 4-wheel wagon (like a miniature hay wagon) that I used to haul the separated hive pieces from the bee yard to my pickup.
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