The CAT Scale I used at a truck stop has three separate segments that allow having each of the 3 axles on different scale segments for 3 axle weights in a single pass ($9). I then went to the parking lot, unhitched the trailer, and went back to the scale to get the numbers for just the TV as a "re-weigh" for $1 (I'll post my exact results when I have time to write it up).
Here's where they tell you how to do it:
http://catscale.com/how-to-weigh