The backpack weight a hiker is capable of carrying depends on several factors. These include the hiker's weight, body mass index (BMI), fitness, and training. It can also depend on the terrain on which the hiker travels, e.g., off-trail or on-trail. However, online advice has tended to focus on the hiker's weight and suggests that pack weight should be a certain percentage of the hiker's weight. We developed a model of how the ability of a hiker to carry a backpack depends on the weight of the hiker. Modeling such real-life situations helps grab the attention of students in introductory physics. We have expanded on our earlier idea and present a more sophisticated model of an adult backpacker. In particular, we generalize our model for scaling of the human frame, and investigate how the ability to carry a backpack (within our model) varies with the form of scaling used.