|The d4 casualty counters in action. You can see the combination of lost bases with the dice hits allowing the units to be visually worn down|
My OHW units are formed of 6 DBx bases set in two rows of three. As a game progresses, whenever a unit takes 5 hits or more it loses a base from the rear rank. By taking from the rear rank the frontage is maintained (this is pretty key to the rules) but by keeping at least one base in the rear rank, the unit's depth can also be maintained. And to keep track of the hits taken by units before losing a base I use d4 dice sitting behind the damaged unit. I was pleased to find a dozen d4 for £2.99 on Amazon, helpful as most OHW scenarios feature 6 units per side.
Not the most revolutionary change to OHW but it works for me!