Unlike summer, you might be chasing sun rather than shade. Most of the main areas have sun until early afternoon. Be prepared for freezing temperatures at night. French Cattle Ranch could have snow at the base still. The old road where most of the free camping is located is still closed (with a gate) at that point, so you'll probably have to use the USFS campground at the bottom of the canyon. May tends to have more rain as well. Ten Sleep is a cool place though. You'll have a blast if the weather holds.