I use draft horses and ponies on my homestead. I get along well with them but there is a lot to learn. Please do not tie random animals to objects until you have some good training under your belt. I use a sled a lot, but using wheels has a significant advantage--I can get more work done with a smaller animal.
The best resource I know of is the Draft Animal Power Network. I was just at their Field Days in New York and it's a great and encouraging organization. They have a map with teachers around the world. Mostly horses, mules, and oxen.
Here's a Vimeo video of John Erskine, who lives near me and has been a huge help.
https://vimeo.com/showcase/2692792/video/76105043
Donn Hewes in NY is another great resource.
I love draft horses and find them a pleasure to be around. If you don't love them, it's probably not worth keeping them. Happy to talk draft equines with anyone if you want more specifics.
Alexia Allen
Hawthorn Farm in Woodinville, WA