Re: combo slatted rack/screen bottom board
I believe the space from the top edge of a Brushy Mountain Slatted Rack to the slats and front board is about 1/4". I use a reduced entrance routed into the front board. The bees walk up an incline and then onto the screen.
If making these again I would use a hardwood or mahogany for the front and back pieces. I used 2x3's for my nuc stands but I would use 2x4's for all side pieces of five frame and full size stands.
This is one of my "Contemporary Hive Stands"using PVC pipe for "slats.
On one or two of my stands I placed screen over the pvc pipe where the front board would be. With a reduced entrance like mine I don't think the "mezzanine" serves its original purpose.
BeeCurious............... Trying to think inside the box...