Transporting units should not affect the profession/promotion system. We make a tank driver profession and it can get a certain set of promotions. If artillery should gain different promotions, then we will have an artillery driver profession in addition to the tank driver profession. What you are saying is that we need some simple "hide 0 power units" or something like that. That would be a good thing in general. Changing the size of the art is also a good idea. We can also make a virtual unit, which contains all the empty vehicles on the plot. We have a bunch of possible solutions for issues like that. That is one reason why I said it's a concept proposal, not a solution.