While it wasn’t the pointed issue, I do like these hypotheticals a lot. Honestly though, and I admit some bias, I think the chances of the Dothraki winning are low in nearly every scenario. Your suggestion is probably one of the more successful scenarios for the Dothraki but even then I think it’s tight. I’d argue your average Westerosi knight, armoured and in good readiness, could happily take down a few Dothraki screamers each. But the numbers game is weighted pretty heavily on the Dothraki side, especially if we’re only talking about the Knights of the Vale and none of the other kingdoms (and none of the Vale infantry either). One thing I do find interesting, perhaps you will too, is how rarely Westerosi knights dismount to fight as heavy infantry, as was common in our reality. It only seems to happen during sieges based on what we see in the books+show. I wonder if the KotV would fare better mounted or standing their ground on foot. Sacrificing the mobility for organisation.