You are quite welcome, Cedar Hill.
About your question?
It is a bit hard for me to advice what to do, cause I have no idea of conditions in the area where your bees are at. But will gladly give general instructions to which most beeks can adapt their own situations to. . .
I know what you mean, about your clubs "respected" members, for they are not alone in advocating wide open screens. Even those in the know, or those who should know, often think that this is a "cure all - fit all" device and the best thing since the sliced bread.
As I said many a time, they forgot, or never knew, what SBB were designed for in the first place.
I keep my screens, bottom drawers, closed year round and in winter I block them with Styrofoam. The only time I open them, about half an inch, is when they, bees, start to beard in the evening while ripening honey, or in the Summer's heat.
One has to put it in ones mind, that the SBB is under the hive solely as a tool to control Varroa and is NOT a ventilation device!
About moisture problems on the floor?
I would not concern myself with moisture or water on the floor. If you, or anybody, pick up any bee-book, one will soon learn that in all those books, all that I know off, writers advise that hives are to be tilted forward, to drain the water out of the hive.
Modern hives are designed, (made cheaply) that the moisture condenses on the walls and therefore water will run down the sides and out. All this is going on away from the bees and without any harm done to them.
If mouldy end-combs are bothersome, one can simply remove them from the hive for the Winter?
This moisture, on the sides and bottom, does not bother them, bees - but bothers us more.
We have to stop keeping bees to our liking, to our standards?! We must learn again, to keep them the way they ware kept a hundred or more years ago. Keep them in the boxes of our liking, but let them live the way nature intended them to live.
All this said, one must have a top entrance, for the moisture to escape. One needs proper insulation over the inner cover to prevent moisture from condensing at the contact with this cold surface. If all is arranged, as it should, no harm will come to the bees.
About wide open bottom entrance?
Again, bottom board was designed with two rims. One is about 3/4", (summer) and a rim of about 3/8", for winter. Most beeks forgot that too, and don't bother to turn the bottom board around when late Fall arrives.
Now, SBB are probably designed with the rim of 3/4" - mine are, cause that is the way I made them. In my case, I use an entrance reducer with about 3/8 x about 6 inches wide opening. One must remember that my bees live in winters with down to -50 degree temperatures. So, a wide open entrance would be a bit much? Especialy because the prevailing wind blows right up the driveway to the front of the hives.
Mice are not a problem, cause 3/8" is too small for them and I never in my 54 years with bees, even once had a mouse in a hive.
So, I would definitely close the drawer on your SBB and perhaps install the mouse guard if you think that one is needed?
Hope that I nailed the areas of your interest? Again, don't worry about moisture or water on bottom board. It is supposed to be there. When you get moisture or water/ice on top - under the inner cover - than one has a good reason to worry about it. Because that is the time when water will drip on the bees and kill them.
Regards,
France