Old but not ancient history.
The FAA has designated ground to sir signals.
So does the Forest Service.
From an older Fireline Handbook
goto page 128.
These are the signals used by Smokejumpers before radios were so dependable or common.
The one we always thought was humorous was "able to ride horse".
They do state that "signals should be 2 by 7 ½ feet or larger".
Although when I jumper, (72-92), they were more like 16 or 18 inches by 7 feet. We weren't abiding apparently.
The only signal I think worth mentioning is double LL's.
LL is used by the FAA also to indicate everyone is OK.
That would be no help needed.
You've had your humor for today.
Yes the jumpers all have radios and GPS nowadays.