Fitting all parts on a page

I'm trying to make a score for concert band, but the parts will cut off after the 17th instrument or so, and I won't be able to see the drum parts at the very bottom. I've decreased the margin sizes quite a bit, but I feel like there must be a better solution to get all the parts visible. I've seen other scores with more parts fitting comfortably, and I wasn't able to locate anything in the handbook that might help.

Thanks!