That’s a wide range as far as gallons go. Keep in mind that you’re probably better off maximizing surface area in contact with the colder surrounding environment in a freezer to get it cold in as short a timeframe as possible, so it would probably work better to have multiple smaller tanks on a common manifold rather than one huge one, unless you have some way of agitating the liquid inside to expose fresh (warm) mix to colder outside surfaces.
Other than that, stage your filtration so you aren’t changing filters every minute, more surface area (look at Sambo Creeck’s offerings) and more CFM on the vacuum side are the way to do it. I posted a thread a while back on how to improve my own winterization process: