my set up is pretty lean. No sensors and not too many gizmo's. But I have an idea to expel the humidity. You may not have the problem I'm having. When my tray floods you should watch my RH sky rocket. You don't have as much moving water so you should be ok.
Anyway, to lower RH when using Co2, I might set up an strong exhaust fan like your 1000cfm'er. Ok maybe 750 or so
Anyway...my Co2 comes on ever 60min for 15 min. There is that 45 min gap. An easy way to expel the humidity without sucking out a lot of Co2 would be to have a damper on that exhaust fan. At minutes 50-59 that big bitch of a fan turns on and sucks out the humid air. The fan and damper close at the 59th minute so at minute 60 you have a sealed room again with Co2 being pumped.
My room is pretty sealed though. Technically a 750cfm fan should make my walls pull inward
Just thinking out loud bro.
How long you gonna veg?