Even if you don't tell what is in your transports, if it is written on your list as ( grey hunters in yellow rhino with flag, or something) there is no doubt if ever asked to prove it. I hide little numbers on all my vehicles, because it helps me differentiate. I'm not a big fan of notes under the transports, or even asking what is in transports (unless it is my opponent's transport

), but if you want to know they should tell you. If you can't trust the person you are playing, why are you player with them? Notations on the list should always denote little intricacies such as this, and full list disclosure is part of the game. This is what my group does and it works great, no dishonesty.
Ruses and trickery are part of the game and disclosure makes that part very difficult. But disclosure keeps people honest. I see both sides of this topic as somewhat valid. Make a house rule, that's compromise.