Drag'em with a shoulder harness. Sure it's work, but they are worth it.
I also carry along a smallrope hoist (mine is an 800#)should I need to haul up hill or over some difficult spot. Not much to carry in my backpack (about 3 pounds) and works like a champ.
Rope hoist like:
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=45076

At the vehilce, I alsohave a small hand winch to winch the deer into the back of the truck.
Like:
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=30329

Tahquamenon