600 pound woman, how to get a weight?

[Guest guest]

I work at a rehab/LTC facility. We currently have a 570lb woman for

rehab, the weight was obatined from the hospital. We want to stay in

accordance to state regulations regarding weighing new admission for 4

weeks until stable as well as obtaining monthly weights. Our scales

only go up to 400lbs. We do not have a freight scale. No bed scale

either that can weigh that much weight. Is there any way to determine

ones weight by measurement. Someone suggested thigh measurements? Any

suggestions would be much appreciated.