3.5 or 5 Gallon DWC?

Hey guys, I'm trying to grow 6 plants in individual bucket DWC systems, but I don't have much vertical space. Could I use shorter, 3.5 gallon DWC buckets and still grow 3-3.5 foot single-cola plants?

Also, I want to get those net-pots that are meant for DWC buckets, should I go with 6", 8" or 10" diameter?

Thanks guys! It's been a while since I have done hydro, so I'm trying to make it pretty easy to manage.

Yes, you could use 3.5 gallon buckets for single-cola plant.
Is your system recurcilating the nutrients?
If so, invest in a rez, you can control all your pods from that 1 rez and it will save you alot of trouble when changing out nutrients and will keep your pH more stable.
I use 5" (125mm) net pots for fully grown plant, so you could use a smaller net pots if needs be.
Edit: any size of net pot from 3" up, will suit your needs