I wonder what defines a mature blah blah blah usable cannabis plant? Enough about the legal stuff, sounds really vague. Anyways, this is what I would do:

I like the idea of splitting the one room into two, making one of them slightly larger (flowering room). You could veg 3 plants for 8 weeks, doing some topping, or LST, or combination of both. Then flower them for 8 weeks, meanwhile starting again. If you can keep an even canopy, you could harvest a good amount. There is a guy on these boards who basically did this, and harvested I think at least 8 oz., maybe 12oz. every 2 months.Here it is

Check that out... Your problem isn't the worst to have... Yeah with this method you might not fill the space totally with plants, but you could invest in more lighting and ventilation, maybe CO2(?),grow medium, etc. to get the bigger buds.:jointsmile: