A friend made a bucket vac system. We've used it twice with very little bee casualty. I have an old small shop vac from walmart. Maybe 20 bucks. I think it's 2.5 hp??? Anyway, we run the hose from it to a shop vac inlet (male end sticking up to receive the hose) that is bolted onto the lid of a 5 gallon bucket. I use duct tape to secure the vac hose on this inlet. A cheap wire mesh strainer, the kind used in the kitchen to separate eggs, is screwed in place under the lid and over the inlet hose to prevent bees from being sucked out of the bucket and into the vac. On the other side of the lid, another shop vac inlet is bolted. This one is a female end that is sized to receive another shop vac hose. This is the hose we use to suck up bees. There is a small hole cut in the lid with screen on the inside to keep bees from getting out. On the outside of this hole is a piece of plastic held in place with one screw. I can make more or lesson suction by adjusting the size of the opening.
Once the bucket is crowded with bees, or we need to take a break, I remove the lid with hoses attached and replace it with another lid. This lid has a large hole in the middle of it that is covered by screen. The bees will be cooler in this bucket and can be transported easily. I was concerned because we are using a smaller hose. I think it is 1.5 inch. But the bees didn't seem to mind on either job.