I don't have enough indoor experience to guide you. I did a few outdoor grows but obviously smell was not the concern.

I am gearing up for an indoor setup and have been researching this issue, as odor is my number one concern. From everything I've read the carbon scrubber should do the trick. If your plants are in the open then there is no way to control airflow unless you have a big enough fan. If you are able to contain the grow then you should be OK with a scrubber.

I am wondering if I should just pop for an inline ozone generator. The carbon filter is going to set me back at ~$100 / year and the the 1000 c.s.f. ozonator another ~$200. I can get an inline ozone light for $350. But that does need replacement bulbs every 2 years at $60 / bulb which is still cheaper than the replacement cost of the carbon filter so setup and running costs of the inline ozonator is slightly less.

I don't think you need a bigger tent unless you want to grow more/bigger plants. Just do a better job estimating the grow cycle. How long did you veg and how tall where they when you switched to flower? You might consider a scrog setup as this will contain the height. Even if they grow out of control you will have maintained most of the overgrowth on the screen.