You’re’ good with the T8…it’s always better to oversize than be under. This way you can run that T8 at 50% and get the circulation you need. Plus, when you do need the carbon filter, you will still be getting good circulation because adding the filter does reduce the efficiency of the fan, and you can bump up the speed on your T8 a couple notches. Don’t be afraid to turn that thing up a couple notches now (after removing the carbon filter) to see what impact that has as well.
Do the walls of your tent slightly suck in with it closed? If not, crank your T8 up some.
For what you have, I would think the fans you have in the tent are good. You may need to reconfigure there orientation when the plants get bigger though.