I've done a fair amount of loaded touring on a cyclocross bike (Surly Cross Check). Heel strike was not a problem with a decent rack. The frame flexed a bit under expedition loads, but it wasn't a big deal. I had zero issues with that bike and would still be riding it if it hadn't been run over by a car.
I have a phantom cross check which I raced cross on. It’s a true cross bike, I.e. built for 32mm tire clearance, relatively quick geometry, top routed cables. It’s mean for cyclocross not gravel, not touring.
it’s a different bike from a Surly Cross check which is not a cyclocross bike in the UCI sense. I’ve raced gravel, and toured with the phantom, but it’s not the ideal touring platform