It sounds like you have the ability to split woodwind and brass every day. If that is an option, I would say go for two bands and split as often as possible. When I was in a similar situation (82 in a 7th grade band), we found great success with this split, only combining once they were ready, and even then it would be at max once a week.

The answer to your question also largely depends on the kids. If you think they are (relatively) well behaved, then a big class won't matter as much as you think.

Good Luck!