I've done 2.25 x 3.25 sheets in a two-reel stainless tank. Just stick one sheet at a time in there and knock yourself out. It's slower doing only one sheet at a time, but it does work and if you have the tanks, you're good to go with no additional cost.
Another option, which I have not attempted, is the 'taco method' where you put a loose rubber band around the film so that it makes a taco-shape. Insert multiple film tacos in a tank and close 'er up.
- Randy