Colors coordinated to teams, perhaps? Most dyes are expensive but as we are in the summer months we should be able to craft our own with trimmings from plants otherwise used for herbs and poultices.

[ A few other notations on paper- adding to the list of things they need.

First: alcohol. Now: rainbow snow war? ]

If you are able to get The Iron Bull interested in this? He would likely be happy to help see it done, and done well.