And of course this begs the question: what's wrong with 4 digit addresses? Every locomotive I have has the cab number as the address.
I use 4 digit addressing for individual locomotives, and two digits for consists. MRC Prodigy system is essentially limited to two digit addresses. When a three digit road number is involved, I add a leading zero to the number (0602). Normally, I have no more than two consists running at a time, so I find it easy to track them.
If one is operating more than several consists at a time it could get complicated, I guess.