From: Lower Saxony Germany
Does seem gamey. But as history and the links posted here dummy units were often used. Quite often with success.
Of course in a PBEM game house rules, where no empty units can be created, can apply.
Units on board ships, well this is a bit more difficult. Prior the Normandy Landings, the fear of information being leaked as the troops boarded their ships was quite large. The area around ports was sealed off. No information gaining was possible, thus information being passed on, by informants was null.
Thus ships would have been sailing out of port but no information would have been gained as to what "cargo" was on each ship.
It would be nice of course to see what units are being transported, but I feel it's part of the fun awaiting an invasion. Not knowing if it is the real thing.
Land units can be "spied" on by recon flights, cavalry units near the frontline.
"It is not enough to expect a man to pay for the best, you must also give him what he pays for." Alfred Dunhill