Hi Tom,

I see your issue, it might not be possible to change the multiple customer tag behavior without customization in developer mode.  

However, could creating a custom filter in the search bar fulfill your needs in sorting customers? 

You can create and save custom filters in the search dropdown menu while in list view for customers in the CRM, (this is also possible in Contacts app btw)

You can sort by and stack any fields including tags and use logical operators like =, !=, contains, etc. to create a sorting filter that fits your needs. Then "save current search" to save your filter for regular use, and even share it with other users or make it the default. This way you can group customers in a precise and flexible way without depending entirely on tags. 

This is a bit of a workaround but it might solve your business flow issue while avoiding any customization or coding etc.

Hope this helps.