Good question!
It actually gives me a chance to point out (maybe for the first time…?) that anyone who gets hit by the curse actually gets a huge strength boost. If we put a curse victim next to a regular human, side-by-side, the victim can haul them around like it’s child’s play. This helps their climbing skills, and helps them blend in with the others their size who are more adjusted to the trials of living at less than four inches in height.
With BL, this AU has both brothers living at the same size for their entire lives. This didn’t even happen in canon, with the way Sam took off to go to college. So here, they’ve lived and worked together for survival since the very beginning. There isn’t much question between them who does what, and all their trips for supplies are planned out and done by instinct. That doesn’t mean they won’t joke around; when Dean’s taking too long climbing up, Sam has a habit of grabbing his older brother by his jacket collar and hauling him up… kicking all the way.