I have my snakes and rats in the same room, I feed my snakes when I'm cleaning out my rat and mouse cages. It seems to give them that much more of a feeding response.
I've always had a major problem with pine bedding and rats / mice. The pine smell is toxic to them, I had rats dropping like flies with pine bedding, just falling over dead. I've since switched to shredded paper, don't have any deaths now. And now that I've been using free shredded paper from work it's hard to justify the cost of any kind of other bedding. Pine chips, bedding pellets, commercial paper bedding, etc. is the number one major expense of breeding rats and mice. If you can get the bedding for free it will save you a lot of money.
Also, I find it's best to spray out the rat tubs every week with some kind of antibacterial to keep the smells down, you can't just change out bedding and expect the smells to go away. I used diluted Chlorhexidine, I've been using the same gallon for a long time, you can really dilute it down with water and it goes a long way. I just spray, let it soak for about five minutes, then spray out with water and dry with a towel. I do it every time I change the bedding, at least once per week. If I had more time I'd do it twice a week.