I think larger units are enough if they only overlap the tile above them, like the halberdier in the latest verion (the halberd overlaps the upper tile).
however in Starwars version i think a star destroyer must be at least 2x2 conpared to the 1x1 xwing
And also in fantasy version if we have an enormous monster that could be 2x2 - but that must be very rare unit. The others , dragons and so on, should overlap only the upper tile.
but i think uneven "base" sizes like 2x1 or 1x2 are so confusing in movement so i have to BAN these sizes from the games.
only overlapping can be accepted (to top tile and we maybe can try it to the right).
maybe i will try the chariot as a little overlapping to right...