parent nodes: An Important Note about size and weight | Module
Basic Fantasy is a system designed around playing human, or roughly human, sized characters. This is a campaign where you play a mink, which is far smaller.
Rather than cover all nuance, there are a few blanket statements that can be made.
For the purposes of carry weight, remove the unit of measurement(pounds) and instead assume a more meta approach that those numbers represent carry points. However! In the case of lifting objects and the such, this does not apply, and it is up to the GM to determine whether or not a mink could feasibly lift various objects.
For the purposes of movement, measurements remain largely as they are, however in theory, up to four mink may occupy a single 5' by 5' square if they so desire.