I'm not sure I would make up mating nucs. If you are trying to rebuild your hive numbers why not just make up regular nucs let them build up and then split again? What are you going with a bunch of queens from mating nucs if you don't have enough bees to make up hives with? When you make up smaller nucs for mating purposes it often helps to move them to another yard because they can't afford to loose many bees back to the parent hive. Keeping them closed up for a couple days does help some but, you will still loose some bees back to the parent hive once you release them. Since you lost so many hives, I think you would be better off making fewer stronger nucs until you can build back up some. JMHO