I realise that there probably isn't a science to this, but a few opinions and suggestions would be helpful.
Binky is feeding quite happily, she takes both salmon and pinkies (I cut them into 3 pieces) from tongs. In fact, she's more adept at striking at the food than I am at keeping it out of reach... First piece of pinkie half an hour ago she got from 3" away, that's about 25% of her length. The second bit I made her work a bit more by keeping it out of reach until she'd done a length of the viv, then she struck that as well. She kept hunting for more for a couple of minutes, but she had had her lot for tonight.

First, is there anything wrong with making her hunt? I figure it's natural and can't be bad.

Second, how much should we feed her at 12-13 inches? I've read about others feeding 3 pinkies a week, but no indication of the size of the snakes they're feeding. Obviously we don't want to overfeed or underfeed (I know she won't starve but we want her to grow).