I recently finished a book by Jacques Clouteau chronicling its pilgrimage to Saint-Jacques of Compostelle accompanied by a donkey transporting his equipment. His argument for choosing the animal was that it could transport more material than a backpack but was slower and more stable than a bicycle. This made me wonder if a compact mechanical "mule" following a trekker was feasible.
Then I remembered the Chinese wheelbarrow, a variant of wheelbarrow with a single centrally-mounted wheel which is more agile and less tiring than the occidental variant with its forward-mounted wheel. My concept is more or less the rear-end of a bicycle towed by the trekker with an abdominal belt. There is some similarities with the joëlette, a trekking wheelchair resembling a sedan chair with a wheel underneath.