Hmm, tough one, seems to me altitude is money (energy) in the bank. I would agree, spoilers off, best glide, but I don't fly gliders.
It is a tough one to figure out in one’s head. The physics of flying in ground effect are well understood by someone, somewhere, but as a power pilot there’s no way to experience it in a way that makes ‘jumping a fence’ a possibility.
Glider pilots, especially those flying high performance gliders, experience energy as a combination of speed and altitude called total energy (TE). There’s actually instrumentation that provides a continuous readout of TE based not only on speed and altitude but that also integrates the vertical movement of the airmass. The ‘readout’ typically takes the form of a continuous audio tone that tells the pilot, moment to moment, the rate at which they are gaining energy or losing energy and whether they are flying at the optimal speed for the conditions.
All of this continuous calculation is pretty straight forward with current digital technology and miniature pressure transducers. It seemed like magic back in the day when it was done with a pitot tube-like device, a variometer and some tuned constrictors. Essentially an pneumatic analog computer sans electronics.
Anyway, glider pilots that take fly their ship down into ground effect with a little extra speed (and no spoilers or landing flaps) will actually feel the aircraft accelerate slightly as it enters ground effect. Less AOA is required in ground effect and there is less drag than level flight out of ground effect and that change can be felt in the seat of the pants.
At that point one can fly along in ground effect for a considerable distance as one slowly pitches up to maintain altitude as the speed bleeds off.
At some point in that exercise, one could still have enough energy to pull up over a short fence and that point would be further than the point would be if ‘best L/D’ was maintained from the same point on final (it’s rarely best L/D due to wind).
However, the pull up over the fence would probably be ballistic-like followed by a hard landing on the other side where the pilot would probably be slightly surprised in being unable to completely arrest the descent.
Question I wonder about is whether the TE instrumentation would accurately reflect the TE profile of the ground effect maneuver? Personally, turning off the TE audio output was part of my pre-landing checklist. It was a way of totally committing to the landing rather than being distracted by some low level thermal or vertical gust.
