Regarding the turnback, I have nothing to add, I'm not someone who should be trying it (in my opinion)...However I'm bemused by the obsession with runways.
IF one has to turnback, AND it's a bit marginal, surely you stick it anywhere you like on the damn airfield? Who needs a runway - anywhere's probably better than the average field, and beats the hell out of dying trying to align some tarmac - even if you have to bounce across some taxiways, demolish some cones etc.