Mapping and Measuring - Paces

I recently picked up an old used copy of Sleightholme's Better Boat Handling.  I had some trouble with docking this summer and it seemed like it might be a worthwhile read over the winter to build up a set of drills to run in the spring.  I haven't sat down and read it yet but I flipped through and looked at some exercises.  On page 22 it suggested:

Exercise 3: Distance judging

Whenever you are out walking and the opportunity occurs, note objects ahead such as typical two-story buildings, people, cars, gates, etc.  Guess their distance and then count your paces.  It is not merely size of distant objects but detail that gives the clue to distance.  A window, for instance, loses its bars as distance increases, then its rectangular form, and then finally it becomes a dot.

Lack of intuition about distances is a serious problem I have had - many canonical-ish instructions in docking or man-overboard drills measure distances in boat-lengths.  I know how long the boat is in feet, but projecting that out multiple times across the water is more difficult.  So I took note of this exercise and have started playing with it; I can do it even if I can't put a crew together for a given day, or the weather's bad, or whatever.  It seems like it would also be useful for anyone running wilderness encounters.  How much detail can you make out about a group of people and/or orcs at, say, 50 yards with the naked eye? (see also this old post)

The mention of measuring distances in paces also got me thinking about the dungeon game.  If I tell the players that the room is 30' by 40', how did they determine that?  I have never stopped the game to ask my players how they want to measure a room.  The default dungeon exploration speed is low enough that I could definitely see pacing the length and width of the room being viable for getting pretty accurate measurements within the allotted time.  But doing this would also expose you to danger from traps or enemies in the room.  So now I'm wondering whether I just want to give descriptions like "big, longer away from you than it is wide" and "small room" up until they have paced it.  Or give them estimated distances in tens of feet, but with a roll for error, and then if they pace it they can get accurate distances?  idk.

I also think it would be fun to give room sizes and distances in paces instead of feet.  Just like using stone for encumbrance, it's a quaint and evocative unit with a little bit of slop.

As usual, this led down a shallow wikipedia rabbithole, with a couple of interesting findings:

• Alexander the Great brought specialist pace-counters along with his army to measure distances, and their accuracy was so good that some now think they must have had an odometer.  How much does a specialist bematist demand in monthly wages, I wonder?
  
• You know those wheels surveyors use to measure distances?  Another name for them is a "waywiser".  I love it - it's alliterative and very Olde English.  If you put them on your equipment table, definitely use that name.
• Apparently pace-counting is still used by the military and they use beads on a string to help keep track of large counts.  I did find myself wondering if I were occasionally slipping up with counts up towards a hundred while I was walking my block this morning; these make total sense.