I see that Sheridan Co. just bought an attachment for a skid-steer that is a snow bucket with a hydraulic motor and what looks like a 3" auger at the rear of the bucket, running the width of the bucket out the left side into a chute. The idea is that the skid steer fills the bucket, the operator tilts the bucket back, holds it up at about waist-high, and then people put bags under the spout of the chute whilst the skid-steer operator runs the auger.

Another thing I've seen that is fast to make is a couple sheets of steel welded together at a 90 degree angle. Make 'em each about 2' wide and about 6' long. Put a steel angle-iron frame under these - set up the frame so that the 90-degree V is tilted off to one side a bit.

Skid-steer loads this with sand. One person puts a bag under the point of the V, another one uses a garden hoe to pull sand down to the bag.