I will guess that your high percentage of females may be due to a low stress environment you had them in for the first 3 weeks. I hope mine turn out the same. I have eight White Widows going right now and I only need one to be male for some extra seeds

If you have a dark spot to put the plants. You can rotate them. You can run the light 24hrs with 12hrs for each set of plants. That's the only thing I can think of since you don't have any more room under those lights. Good Luck.
Check out my thread "White Widow Pic". You can see I can easily house your extra plants