If increasing the storage capacity of the boxes does not align with your design philosophy, could we consider adding specialized boxes for storing gems or runes instead? This would enrich the variety of boxes and provide more options for decorating the homestead, avoiding it being filled with long boxes (although this may still be difficult to avoid).
The box for storing gems could be packaged as a “display case”.
The box for storing runes could be packaged as an “altar” or “magic circle”, for example.