Contemplating putting 2 plants outside. I have 8 i...

Tbh you're probably fine because you're in 3-gallon pots but I would suggest getting a scrog ahead of time, makes managing and spreading that much canopy easier. Be sure not to veg for too long, be sure to save 2-3x the plants height in empty space above the plants to accommodate for the preflower stretch.

Honestly you could go either way. if you keep them all throw a net up there and do a SOG

Yes 8 is to many id go with only half that next time. 6 is doable but gonna be super crowded. I use 5gallon pots in a 3x4 with the Mars Hydro tsw2000 also and i get crowded with 4 plants. And i only veg for 4-5 weeks. Also have to throw another light in during flowering.

Your plants are telling you they have enough light as is growmie. I would make sure to train them low, keep your canopy even and I think you got this. (Trellis possibly?) Hope this helps.

Yes, I'd say your best options are to either take some plants outside to make space or to flip the lights to 12/12 and hope it induces faster flowering so they stay small (might not work if they're autos, but should reduce growth anyway due to less light). If you leave them all in you'll get less yield per plant as they compete for light. However... If it's cold right now where you live I would think twice about putting anything outside just yet - your returns would be basically non-existent this stage, certainly where I live at least. You're basically making an expensive version of Sea of Green (SOG) using autos as things stand, but that's preferable to chucking healthy plants outside if it's too cold and dark and getting nothing from them. Good luck!

Id throw 3 or 4 of them outside make sure harden them off first.

Yes its definitely too many. I think four plants will fill up the space on their own because they will soon start growing in height. 5 or 6 might get crammed but i suggest attempting defoliation/lollipopping so that there wont be wasted energy on parts of the plant that will never see light. Good luck on your grow 🙂