AD620, digitally adjusted reference pin


I use AD620 in order to amplify my loadcell signal. I have +/-15V present. I regulate these voltages to 10V and -11V. I use 10V to excite loadcell. Also I use 10V to power AD620 and OP177 op-amps. (There is a filtering circuit after AD620 with couple of OP177's). I use -11V to power OP177 and AD620.
With a help of a POT between -11V and zero volts I adjust reference pin voltage of AD620. I use OP177 to buffer POT.

My problem is that I need to change this system and put digitally adjustable reference pin voltage.

I am planning to use AD7391. BUT I need extra 5V supply. This supply must be very pricise I think. Right now I have a precision 10V source. How can I use this to power AD7391. Also I need opto-coupler to control AD7391.

AD7391 consumes around 100uA, optocouplers can be around couple of mA. Can I just use reference IC without boosting the output.