How about just randomizing who goes first? 50-50 chance you'll go first, then the enemy units. Or enemy first, then your units.
Or to add more drama, randomize every 2 turns (4 movement phases - 2 of your turns and 2 enemy turns).
So, movement phases could go as follows:
You, You, Enemy, Enemy or
Enemy, Enemy, You, You or
You, Enemy, You, Enemy or
Enemy, You, Enemy, You or
You, Enemy, Enemy, You or
Enemy, You, You, Enemy