Mite amount is high. If you make split you may use this method. It seems reasonable. Otherwise at autumn you may have catastrophe in front of you. http://www.xs4all.nl/~jtemp/dronemethod.html
Let them raise a frame of drone larvas
Move hive 10 feet away.
Put empty hive in old site and there is queen and drone larva frame.
Bees fly themselves into the new hive. Mites go into cells when it is time to cap them. When all drones are capped take frame away and destroy larvas with water jet. Put frame into queen's hive and let it lay eggs into drone cells.
Then you have a hive half which have no queen. They start to raise emergengy queen. When after one week larvae are away split that hive again and put the dronelarva frame inside. So mites have only dronelarvas and they go into brood cells. So you have again pure guater of bees and you may put them together to hive which have the queen, or give them another queen.
When the rest brood have emerged in "second nuc" handle it with oxalic or give to it "trap frame". During 3 weeks you get rip of mites.
You must kill the rest drone pupas from frames because they live 4 weeks and they contain mites.