This may be one of the easiest dog chews you can make without stinking up the house. It does take awhile to cook/dehydrate, so try to allocate enough time in your day to monitor the oven: in total you'll need 6hrs.
Preheat oven to 250 degrees fahrenheit. Cut up sweet potato into slices or sticks depending on what you want to do. I cut them between 0.5-1cm thick just to see how it altered the cooking time and it wasn't too dramatic. Once you're done cutting it up, lay in a single layer on baking sheets! If the oven is done preheating then place it in the oven for 2.5-3hrs. Flip then put back in the oven for another 2.5-3 hrs. Remove from oven and let cool on a drying rack. Place in a jar and give to your dogs for a healthy chew treat! If you want to prolong the shelf life then I find putting a bit of dry rice in the bottom keeps them dried out better.
Have you tried this? Let me know how it went!