On my bottomless hives I use stands that put the hives about 10 inches off the ground. I use slatted racks as a barrier (guard) on the underside of the hive and also to rise it a little further above the ground. IMO, putting the hive body directly on the stand without some barrier is asking for trouble. I make my stands so I can slide a 1/4 inch thick piece of plywood under it to close it up, regulate the size of the entrance, and monitor varroa mites (which I can't find any evidence of).