Probably 4 D16-6, just love that quad mount. Another possibility results from Hobbylinc putting Aerotech 18-20 cases on sale for $15 a few months ago. I got an order in but the went backordered. They finally delivered the last of two cases last week so now I have four, so D24s would be a ride. I also got many F39s when a hobby shop closed, it would be very nice on that but the quad first.