I don't know how it is where you are, but I have two Clydesdale farms within an hour of me. They mostly do paid jobs, but maybe your project might be interesting enough if you have such a horse farm near you.
I know the owner of one of the farms (a funeral home) collects all kinds of carriages, and I would see him interested in at least trying something like that out. I took pictures of a mid-1800's hearse he had, that I used to help me with a painting I did that included a carriage from that era, for the shine/reflections in the polished exterior/hardware/wheels/paintjob/etc.
There are collectors in every field. And I bet also carriage horse associations. Here is a couple I found in your state.http://www.bitsiowa.org/http://www.midiowadriving.org/
Can't wait to see it finished, and behind a couple of horses!