My husband is 6'2" and could not stand up straight in our former 16'
Scamp or our current Deluxe 19'
Scamp. He can stand up in the 19' Scamp only in the area where the bathroom door and the steps to the loft are. That's where the Scamp ceiling rises up for the loft.
Remember there is often an air conditioner which robs some of the headroom. And people are usually wearing shoes or boots which makes them up to an inch taller.
Still and all, most of the time he is not standing in the Scamp so it turns out not to be a really big deal. And I'm only 5'4" so it works fine for me!

Fran