[narwan]

The main reason why I left out transports in my proposal is that they serve other uses besides transporting units and can be easily abused.
By not using these you can greatly simplify the scenario. You could use ammo cannisters and have these picked up, but how would you translate that in victory conditions within the game? Same would be with the engineers, it does add flavor but will be hard to put into victory conditions terms. In other words, how will you penalize a player who doesn't do as he should? How does it translate into a 'loss'?
Also, if bought through the NVA screen, all US forces will be able to target it, not just the engineers.
I'm the type of player myself who looks for 'loopholes' and unconventional uses of units and I'm trying to do the same here, look trought the eyes of the 'abusive' player and limit his options as much as possible.