I’m sorry I didn’t answer this earlier. I’m on a trip to Florida right now.
I wouldn’t recommend using the slow cooker for something that small, no. I did it on a blue tit and the skull essentially disintegrated. For something that small I would use a more natural decomp method.
Maybe start by putting the whole animal in a small bucket with some grass shavings, maybe woodchips, and leaving it out in the sun in a warm place. Put some screen or chicken wire over the bucket so that crows and other scavangers don’t take it. Or You can leave the lid on the bucket (but don’t seal it air tight). You want the bugs to be able to get in. Try to keep it moist but not wet. Pour a bit of water in the bucket just enough so that it soaks into the woodchips/dirt/grass. Leave it like that for a week and check up on it occasionally.
Ants! They’re no good for something this small if you want all the bones, they’ll steal the finger bones and the teeth, but a big active anthill is great for sq.uirrel size and up. You want to cage the dead thing in with mesh so nothing else steals it.