Just so you know, I've found that my Aussie saddle from DownUnder is a little narrow (the tree is set at "wide") for my exceedingly wide Arab so I have doubts that it would be wide enough for your draft. It fits my Arab perfectly through the back (very flatbacked and wide) but her shoulders are just a smidge too wide for it. It isn't bad enough to cause her issues but it might for a bigger horse.
That being said, my Aussie is SO comfy. It's my favoritest saddle ever. If one works for him, I definitely recommend it.
Of course, DownUnder might have draft options, I've just never needed to look into them.