I voted under 2000 cause I've done some 1950ft runways. But the plane has to be light and the approaches have to be clear. I think I could consider something like 1600ft of pavement if there's endless space on both ends for safety factor. But most of the time, there's not so you need extra runway for safety margin.
Here's landing at Braden with 1950ft:
Also flew into Andover Aeroflex, similar length, recently with @carusoam for some practice and credit in the 99s challenge.
But realistically, anything under 3000ft needs to be deliberate and planned. Not doing something that short spur of the moment.