Keep in mind when switching over food is the snake doesn't want to eat the rat it will refuse it once it realizes the mice ain't coming it will eventually go for the rats. If you stop trying and give it what it wants (mice) it learns it only has to wait until it gets what it wants and that can make it even harder the next time around.

If it was my tank I would get rid of the lamps and add underank heaters. Easier to maintain proper heat range.

How old is the snake?