Well, you could leave only the red grade, and script the troops for the turquoise color. RedHeavenHero has a feature for the green player in the 4th mission of his campaign, "Empire of the Unicorn." He hires regular humans, but a script transforms them into the troops needed for the plot. That is, such a script could, for example, transform red troops in the turquoise player's armies into white ones, while the player would hire their own red troops.
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By the way, the map is very similar to the standard ones. So, you did a good job!)