Really, what's the point of asking about that tanking up? It can't be the two disputed truck sightings, as it doesn't fit in any time frame (if it was TB going to the gas station, he wouldn't meet DM and MS for at least 30 minutes since they passed the Supersucker in Yukon).
It could be some sort of a last ditch attempt to falsify or confirm Smich's testimony. Otherwise, if they want to reconstruct everything and draw inferences, it's going to take awhile and will come to the same seized state that we have here - whether Smich knew or not. And there is no single decisive evidence for that. It really is a matter of belief.
So far, the WS anti-popularity contest runs @ 93.5% for DM-M1 and 74% MS-M1. In other words, there is ~ 6.5% and 26% chance that any single juror believes they deserve a lesser charge. How that will transform into a collegiate decision is a different and interesting Q. IMO, they'll be judged on extremes. 2nd degree and manslaughter are very unlikely for either of the two.
I find it intriguing that the judge brought up the two dogs and a bowl of dog food example with the inference that one or both of the dogs ate it. Wasn't Millard reported eating dog biscuits? Did Millard empty the bowl? Was it deliberate?