I like option #3, myself. At the volume I work at (2 or 4 gal at a time), the vertical cuts are easy enough to do with a regular knife. It's the horizontal cuts that are difficult.
Another option would be selling sets of 2 frames, each wired at 1/2" spacing, that could be locked together somehow, in an offset pattern, so that when together they cut at 1/4". If this setup could also be made so that you could use it for horizontal plus vertical cuts, you'd be totally set for any situation.