It might be possible!
While I was working on NS, I came upon two issues. One, the cav gloves wouldn't sit properly on the model and would cause a lot of clipping due to the fact that it would sit on top of the hand model. Using the .brf editor, I was able to stretch and skew the glove so it goes over the hand and reduce the amount of clipping it caused.
The second issue was when I was working on the U.S. Grant uniform, the coat would sit above the pants and leave blank or dark space in between, again, I had to stretch the model (pants) in order for it work. I didn't notice any impact in the animations after doing this.
For example, lets say I want to replace the British captain pants with the French sailor pants.
1. Open the Brf editor.
2. I've selected the captains coat and the pants, as you can see, we have a problem.
3. Select only the pants and then click on "selected" then "Roto-translate-rescale".
4. For this test, I figured it was better to stretch the pants rather than adjust the hight of the pant model. Uncheck the "uniform" box and adjust the Y to 110.00. This will stretch the pants to make them longer.
5. Click on pants and coat and note the difference. As you can see, now we have another problem.
6. Click on only the pants again and follow step 3.
7. Adjust the Z value, for this test I set the value to 0.0150.
8. View the jacket and pants together again.
Here's the in-game test screen shot:
Obviously he needs boots but that can be fixed via the Brf editor. This is just to illustrate that you can play around with the model a bit without having to physically edit it.