Adding units to extended fields?

So far I've been able to get SketchUp and SpaceDesign up and running for what I want to do and the results look fairly acceptable by now.

I have one question though, it's the one in the title, is it possible to add units to extended fields, apart from the normally working currency sign in extended currency fields?

Let's take a specific example, I have a bunch of components and weights, if I want to display the weight of a type of component along with a unit I can do that like this:
((%DC: weight%.round(3)).to_s + " kg")
So I'll get "XX.X kg", for example "1.253 kg".
If I want to have [,] instead of the [.] I just write this instead:
((%DC: weight%.round(3)).to_s + " kg").sub! '.', ','
I'll get "XX,X kg", for example "1,253 kg" now, so that's not a problem either.

But If I put in the units for individual weights, I will want to do the same for extended weights, because that's where I get the total, and having the unit in the total is most important.
As I read and tried however, $count and extended fields are not available for further processing, so I can neither make an extended field myself by using $count, nor can I get the unit into the extended field afterwards.
Is there some other way to do this? If not, could a possibility to do this be added?