Yikes! CO2? Bonking a rat on the head? Way to much work and I don't like the idea of having to pre kia my feeder rat's to my snakes,lol. I use to keep rat's and mice as pet's. I'm glad that all of my snakes take f/t. I did have to feed one of my normals live cause she wouldn't eat. I promised myself not to get attached to the food (when driving home to feed) lol.
If, you want to feed f/t I'm sure there are stickies here talking about how they did it? For me, I just kept offering my one normal female a f/t weekly. She refused to strike at it everytime, she would just smell it and move on. After, a few week's of her not eating thou. I read a post saying that you can leave the f/t rat in there tub overnight? And, wouldn't you know the f/t was gone in the morning. Now, she takes the f/t all the time. Maybe you could try this way,too?