A great source for pulk poles is six foot long fiber glass chimney sweep poles. They are already threaded on each end. They are both strong and flexible. The metal threaded chimney sweep end caps for attaching cords can easily be use to attach to a padded waist belt.
Brakes can be made from aluminum sheet stock and an 180 degree hinge fixed to the back of the sled. Keels are made of aluminum angle stock.
I look forward to winter snow travel since I don't have to carry any pack. On slightly crusted snow I can eliminate wearing snow shoes when using a pull behind pulk. Plus in winter you need to carry more and heavier equipment.
I don't know how much weight I have pulled but I know I could not have carried it. Pulks are great for packing out elk quarters.