Rodents farmed for pet snake food (Rethink Priorities)

There are between 4.2 million and 7.8 million pet snakes in the world.
85 million to 2.1 billion vertebrates are killed for pet snake food every year. I think that the true value is more likely to be on the lower end of this range. Most of the vertebrates seem to be farmed mice.
Feeder mice are killed when they are anywhere between 48 hours and more than 9 months old. Most seem to be slaughtered when they are 3–4 weeks old.
Farming of feeder animals seems to involve considerable suffering because they are often living in cramped and possibly unsanitary conditions, which don’t have shelters to hide in, lack daylight and activities.
I haven’t figured out what possible interventions in this space could be particularly promising. It’s possible that the problem is not very tractable.