On the WSS Hunter Gatherer course i did and reviewed ( in case you want to have a search and look at the photos of the fleshing poles ) we used a length Soil pipe ( which i think is 4" diameter ) with two poles cross lashed underneath to support it.
Although usable they did have a tendency to 'slip' , I would suggest drilling two holes and inserting two broom handles to create legs. I would also be tempted to try with a cylinder of a larger diameter although it may prove not to be as productive , worth an experiment i guess.
I think you need a narrowish cyclinder ( say 4"-8" ) and with full length of the skin so at least 4' long , to create a 'nap' and push as much subcutaneous material 'up' so you can take it off with your weapon of choice.
HTH