usual unloaded load cell diagonal voltage?
The diagonal voltage is the Common Mode (CM bias) is not what is amplified, rather the Difference (lateral) voltage in a bridge type load cell.  

Thus the CMRR rejects the CM voltage and the Differential Mode (DM) gain determined by R ratios in an INA (INstrument Amp) configuration of 100x is easily obtained.

The CM voltage bias only needs to be within the CM range of the INA inputs, for any given Vcc.  Then the output also has a CM range where Rail-Rail type outputs are preferred in low voltage systems that need this output swing range. This depends of course on supply voltages available.