Maybe they could set it on Bajor or something to help with costing? Also one or two characters would be fine in each one. Could just have four episodes like the first bunch. Wouldn't necessarily have to be all DS9 characters either?
They could do it for Voyager as well. Or combine both into one series?
Honestly I don't think sets are a huge problem. Lots of DS9 involved people just talking in a room, so some simple set redressing could easily work. Developing sets would probably be the biggest lift beyond convincing CBS that the nostalgia trip was worth the money though. I have to think the old writers and the cast would both jump at the opportunity - at least as a one-time thing.
I'm not a big Voyager fan, but I can see why VOY fans would also want their characters revisited. However, I feel very strongly that there shouldn't be "crossover" shorts. The VOY crew didn't really know anyone on DS9 (or TNG) and for the most part (with the exception of Janeway becoming an admiral, and the unique status of Seven and The Doctor) weren't particularly famous.