My gelding is a real Heinz 57. When I adopted him from a PMU rescue, they told me he was a belgian cross, said he'd be about 16 hds at maturity and gave me a picture of him at 6 mos. with his mother. She looks like maybe she's a TB/Clyde cross. When I looked up the ranch he came from in Canada, his mother was listed as paired with a perch/paint stallion. All the Belgian stallions were around 16 hds, the perch/paint stallion was 17.2. My gelding is currently 18 hds! Mostly I just tell people he's a draft cross but he's gorgeous so if they ask, I tell them perch/paint/TB/clyde.
Our pony is a large leopard spot so we say he's a POA, could be registered as one through the hardship clause if we wanted to show him in POA shows.