FWIW, I found the actual numbers here, they were actually in the FAA
"airplane fliers handbook"

For a Constant, 9G deceleration (as I mentioned, easily survivable)-

at 50MPH, 9.4 feet
at 75MPH, 18.8 feet
at 100MPH, 37.6 feet

What to take away from this, is you will probably survive a full-stall
landing on just about any surface in your typical light single GA
aircraft... Hell, even in thick bushes or small trees... The key is to
strike A- as slow and B- as shallow as possible.

The risk comes almost invariably when a pilot passes up a "suitable"
landing zone (even the aformentioned tree canopy) for a "better" one
that is marginally outside of his energy-budget's reach... A full
stall 30 feet off the ground while trying to extend a glide will
almost always be fatal... the same full stall just 30 feet lower, even
in on a less than ideal surface, will almost always be survivable...

Something to remember.