Excellent questions that i hardly ever get asked Seedling. I can only legally grow 4 , as you know.
Have been growing in this little room for about 18 years now and have tried all different combinations. Simply put , doing things this way , with my situation, is best . Would advise not to run Sativa's and Indica's at the same time. Different harvest times , growth patterns /stretch, etc. Could mean possible complications with drying , processing etc....if you need to dry in your tent/room, cuz of odor.
That's why i try to grow two different strains that bloom for approx. the same duration. The more strains you throw in the mix, the more complicated things get. Example...my next run will be two similar strains..in Bubba Hash...and Lemon Skittlez. I look at things like breeder times, height , etc. Try and match things up as close as i can. The reason i always grow two strains is for variety , that's all. Any time i did just one , you get tired of it too fast and wish you hadda done different. So, if i were you...being your situation sounds similar to mine , grow four , two different, but similar strains, in the biggest pots you have,..give them as much light as you can afford and deal with , keep your enviro as close to 'ideal' as you can.
Cheers eh.