First off, Brandenburg is going to be used as a general purpose room during the daytime for staff, for example to print and hand out the fursuit badges. When the Dealers' Den closes, however, artists will be able to store their goods in this room for the night, if they cannot easily take them back to their room.
There is an exit there, but I think it's just a normal exit and isn't alarmed, because we were using that door during the Suhlvester Party last year. But, I don't know the German laws about blocking off exits.
German laws would kindly strangle me to death if I'd block an emergency exit with tables and half a metric ton of plushies, alarmed door or not. Unfortunately I don't have any
exact measurements of this specific niche of the lower lobby, so I cannot tell if there's enough room to place two tables there without blocking off either the fursuit photoshooting in the Holli club next door or the old secondary den. Heck, if I had those measurements, I would have known that there's an emergency exit in the first place!
Well, either way, I'll find a suitable spot for you, PlushFox. After all you only want to sell for a day, anyway, to not miss all the fun stuff happening elsewhere.