Just to clarify on the coco fiber, you mean fine like the dirt? That's usually not too big of a worry since it is such small bits. Still nice to try and reduce it if the rat is wet just so it doesn't irritate too much.
If it was a large number of chunks of coco chip I would worry a bit and try to cut back on how much they swallow.
I've had a couple snakes just sit and take some big breaths after they eat. They're usually the ones that really seem to work at it. Some of my slower eaters have no trouble with it. I do try to keep my feeders dry though when reheating them. Some of mine get fussy if they don't smell enough. lol, so they're in freezer bags while in the spa