Thinking about this, I almost would prefer just fixing the sizes to the unit size, instead of worring about how many troops are in the full strength unit
Have the unit sizes just be platoon, company, batallion, regiment, ect.. Have each size be approximately three times the size of the previous, and dont worry so much about the actual numbers.
Then have the different unit types have different bonuses from the medium infantry baseline, like armour is good on attack, but really penalized in terrain. Stuff like that.
Then tweak the numbers so that a feral regiment gets wasted by an Imperial tech level platoon (or maybe company).
Just some ideas..
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