I dry meats and make my own doggy treats - healthy without preservatives!
I take lean meats and pound them into a flat sheet and lay them on the dehydrator racks. Then when dry cut the dried meat into small bite sized pieces for training.
For chew treats, I don't pound the meat flat (takes longer to dry tho). I also dry my own pigs ears (not oily like the ones from petshops) and started making my own "raw hide" treats - I take pig skin, cut them into 6in squares or rectangles and roll them up then place them in the dehydrator.
I freeze whatever I make so they last longer.
I would stay away from drying anything that is high in fat or with obvious fatty deposits as the fat takes forever to dry and gets rancid faster (especially if you don't freeze). And of course everything gets abit oily!
Never thought about drying sweet potato. Will go get some to try out!