I’ve found that a couple sheets’ worth of paper “Light” and “Heavy” roundels works to disambiguate which tanks/cruisers/battleships/carriers/bombers are which. Not the prettiest option, but sure is the cheapest.
For instance:
Heavy roundels designate - Heavy Artillery (my homebrew artillery tech “Heavy Artillery Doctrine”, same stats except Costs +1, supports two infantry units), Heavy Tanks, Heavy Strategic Bombers, Heavy Cruisers, Heavy Carriers, Heavy Battleships
Light roundels designate - Light Tanks, Light Cruisers, Light Carriers, and I use “Light” roundels to indicate “Fast Battleships” as well, since they move faster than ‘standard’ battleships
