the highest person

You need 7-foot.

However, I"m not sure what you mean by "stacked." Are they each standing on the shoulders of the person below? Stacked sounds like they are perhaps lying on top of each other, like fire wood.

I'd also say "The person on top is waving his right hand." The person on top, not The highest person.

Grammar GeekAre they each standing on the shoulders of the person below?

I meant this. Is there a simpler way to say this? vertically stacked?

Grammar GeekThe person on top, not The highest person

Thank you, GG. How about the person on the top? Is that acceptable?

No, don't use "stacked" at all. That sounds like someone else placed them there. I suppose if they were toy soldiers, you can say that the child stacked them one atop the other, but people are not stacked by another person.

Four 7-foot men formed a human tower, each standing on the shoulders of the one below, and the one at the top/on top, waved from 28 feet up in the air.

Thank you, GG. It's long enough to confuse my brain that I need to carefully word them.

Grammar Geek28 feet

Not quite! About three times the average distance from the shoulder to the top of the head has to be subtracted! I'd estimate 25 feet 6 inches.

It's compensated by the arm extended above the head The arm must be quite long.

I usually wave with my hand at about the level of my face, I think. Although, I may extend my hand way up over my head in a case like that, so it could be from 30 feet if that fellow did the same.

By the way, I have an errant comma in my post. Can you find it?

the one at the top/on top, waved from 28 feet up in the air.

Those who always check my writings know that I suck at commas. Anyway, I think this comma is not needed.

Good job. I'd love to pretent that I put it there as a test for you, but I changed my mind about what I was going to write and didn't go back and fix it.

(Not only is not not needed, it's wrong where it is.)

Thanks, GG.