Yes, multi-units (image includes more than one figure) can convey the feeling of quantity. I played Bonapart II by John Ellis which makes heavy use of multi-units. Although individually they look good, the multiunits REALLY clutter up the map so that if you zoom out to much it becomes very difficult to make out adjacent units.
Multi-units seem to be a little bit redundant IMO since proportion (in terms of quantity, not size) is not specific in CIV --but I haven't played your scenarios leonel, so you may have had better luck.