The pattern of any beam too close to earth such as a Hexbeam at 10ft operated on 20m will be horrible such as decayed front to back front to side and gain then additional ground losses occur simultaneously this is true for any horizontal antenna too close to earth.
Making contacts with other countries via skywave and the 10ft high hexbeam is relative only in the underlying question compared to what?
Rapid switching could reveal that a wire on the ground could have also accomplished the contacts.
It will work sure,, at 10 feet. A dipole 1 foot off the ground will work too.
I was just saying 30 feet is a starting point. If the OP is having success using his HEX that way, then why post a question here?
The replies say that there would be little F/B and the attributes of a HEX or Yagi are wasted at 10 feet.