The horse i'm currently riding is an absolute dear, and well mannered with a good head on his shoulders. His owner(not me) has done a couple competitive trail rides with him, since he was gelded this year and while he stills gets a little flirty he's settling well.
The thing is he's a 16"3 Drum Horse. Definitely not a light breed. I'm not looking to be extremely competitive with him, finishing a limited distance would make me happy. But do you think it would harm his health trying to complete a short endurance ride? Obviously, he would needs lots of conditioning and muscling, and i'm more than willing to spend months getting him to a place where his health wouldn't be harmed, but is this a possibility for a draft horse?
He's getting back into shape now, we're doing lots of trotting and going off road to help him get used to being on the trail with other horses(he's to the point where he's barely bothered until a crowd of more than 20 or 30 horses starts getting a little too close, and even then he just gets excited)
Here's a pic of him from today, to get a sort of idea about his build.