My 2p worth:
A simple change to ukahft rules would sort this out."The firing peg will be a wooden/plastic post that must be securely fixed in the ground, at least 12” must be showing above the ground, the exception being kneeling or standing position" This then gives course setters the option of sticking a short peg in to make the position truly unsupported as intended. This then complies with the current UKAHFT ruling of "1 x unsupported kneeling shot, 35-45mm un-obscured hit zone at 8-35yds". At the moment larger shooters are at a disadvantage as they cant get down to touch the top of the peg, whereas us shorter types and of course juniors can rest their hand easily on top of the peg.