I have cow penned with many a horse but never with a Clydesdale..... I love draft horses... and would have a field of many!!!
My neighbor has several draft horses ,they do carriage rides for the local wineries here . Post SHTF I'm not sure they wii be able to feed them.they rely completely on external sources . It was my recommendation that they strongly consider growing the feed them self, but they've already got too many irons in the fire as it is. literally . I have the space but the land is not that good for growing (which can be fixed) and the water situation here is critical too.( California drought ) If I had my own well and a good GPM I could be persuaded . I have a good water reserve for my self, but not enough for horses . I raise chickens and plan and prepare for their survival and hope to have a brooder or two well before thing's go south. I speculate that at least with a horse one could use a wagon and haul water from local lakes, till they dry up .