These are the 70's triangle cut Halter Tops that will fit most body types. Please measure yourself to make sure these items will work out the way you are hoping.
Donkeys can and do pack 25% of their weight. Make sure you consider the weight in the packing system into the weight carried. Work up to the 25% over time. Please do not think you can buy a donkey, load it the next day and go for a packing trip if it is untrained and unconditioned for the weight.