Yeah, I generally use the "about the same size as the thickest part of the body" rule too, but the more technical rule is about 10% of a snake's body weight. So for your 260 gram snake, the prey item should weigh about 26 grams or so. If he seems really hungry, you could shorten the time between meals to 5 days and bump it up to 20% of his body weight, or 52 grams.

But yeah, you usually don't see too much of a bump with bps, and from those pictures it looks like he could handle a small rat easy. And obviously he did