those distance-to-go boards that you mention exist at all US civil airports
Are you sure about that? I frequent many US civil airports and I guess they must be really small because they sure aren't noticible.
They're optional (and therefore not nearly at "ALL" of them), but not uncommon...
KFJK 31L (on the left side, starting with 11 at the threshold)
KLAX
KORD (Hey! They've got radar! Can anybody telll me, is that an ASR9 on a new tower sitting next to the old ASR7 tower in the background? I have not been keeping up...)
KBOS 27 (I prefer to see the numbers start larger than six though...)
KSFO
KDFW
KDCA
KSMO 21 (Santa Monica, California)
Dave