Pilotage - good point. I will maybe price what the job would cost to bury the wires, then I could extend in to the adjoining paddock and grab another 50m or so.
Monocock- you mention you operate STOL machines - which in particular do you use at the moment? The Zenith CH701 quotes a ground roll of 42m. The new 4 seat CH801 (if and when certified) 88m. The Husky 76m. So to convert ground run to TODR I would guess add another 100m at worst to clear 50'(which is not really an issue), and the maths do seem to work. I take your point about margin for error though.
And yes, you are right about STOL pilot currency, I have around 1000hrs of light GA time and every summer use a 400m strip with a light Cherokee, and fly for a living, so would be fairly confident to try it out (so long as the sums work!!!)
Genghis - yes I know of of an elderly gentleman who operates a Minimax out of 250m where he had previously used a Goldwing microlight canard.
Shortstripper - Thanks for the VP info., and your encouragement.
All good feedback! Keep it coming!