I've been thinking about this a bit, and am planning to go with a tray back ute and 12v electric hoist/winch. Basically drive as close as possible to the hive site, and drop the hive off the tray with the hoist, move forward and repeat. I think you could probably fit 10 to 15 hives on a tray back. The other option I guess would be a tail gate loader and some sort of trolley or in a pinch a trailer with a ramp and trolley.
Paul.