EDIT: I have figured it out (somewhat), so nevermind!

I wrote this in my AddSystem:

However for output that should be unitless, I still get units (which can be cancelled), like this:

The Units package includes various units that are called ton/metric ton/tonne/short tons but not long tons (LT). A long ton is equal to 2240 pounds of weight and is part of the imperial system, so it is also know as the "imperial ton" or the "weight ton".

This unit (the long ton) is used extensively in naval architecture and ocean engineering. I would hope that you consider adding it into the next update of the Units package.

Or perhaps, it would...