Hi Mark,
I would worry about the resolution of the bathroom scales. Mine only give 100 gram resolution. I guess it will depend on how heavy your model is and waht precentage 100 grams is.
My scales resolve to 1 gram.
I have since purchased a device on which i can place the heaviest model. I got it from someone on the web but can't remember where. I will try to find the site.
Here it is:-
http://www.ezbalancer.com/
Regards