How many autoflowers?

You don't need 25L pots for autoflowers. 15-20L pots are probably better. 3 rows of 6 seems reasonable. You probably don't need 1200w for 18 hour operation unless the efficacy is very low. Running them at 800-1000w depending on efficacy of your lights should be fine. This is a good thing. If you ever do photoperiods, your lights are powerful enough to do that in 32 sq ft, too. Dimming lights does improve efficacy of the diode, but drivers are usually the most efficient at full load. Still fewer watts are fewer watts either way on the electric bill. You can give photoperiods a similar vege period (2-3 weeks) as autoflowers and get more consistency in production, if you choose. Autoflowers do their own thing and can vary quite a bit. You can better control the consistency of size of photoperiods, and it'll take the same amount of time, too. They are better plants and probbly better suited to your context too.

Hey, i am currently running 2 automatics in 15l living soil on 0,32 square meters. That would equal 6 automatics/square meter. Your tent is 2,88 square meters, meaning that it would be fine for 18 plants in my case, with 15l pots. You may have bigger plants with 25l pots, but you can still cut off what is too much. If you want to be safe, you can consider going down to 12-15 plants, or use less soil. Good luck!