300-400 lbs sand in the bed - over the axles. take it slow. If stick, higher gears. Auto - try 3 or 2. getting it going is easy - stopping not so much! This is what will bite you. Gear it down as much as you can.
IF it starts to get away from you, and in 4x4, just let go the steering wheel. no gas and NO BRAKES! It will right itself. Don't fight it. then EASE back into the gas (taking the wheel back, of course!)
use the curb or even grass edge. Don't spin the tires if at all possible. snow will actually help vs the slick packed snow/ice.
If you are spinning the tires - get out and toss out some sand.
