I do think your theory's an interesting one, and I'm sure in some places stone circles may have had other uses. however, I am almost certain Meikle Findowie isn't one of them. The tallest stone here is about a metre high, with most of the rest being much smaller. Not obvious in the photos is that inside the main circle is a second ring of much smaller stones

It isn't thought to have had a cairn in it either, just a double circle of stones. As with other sites in the remoter parts of Perthshire, the circles were probably built with smaller stones due to the manpower rquired

Cheers
Andy