LT8316 Feedback question

Hi ADIexpert

my coustomer would like to built a DC 110Vin to 12Vout/5A flyback with LT8316

however, the feedback function of all of the reference design in the datasheet and also EVB  are based on a 3rd winding topology

since my customer already has a 8:1 transformer from legacy projects with similar power handling capability

he would like to use it as a common part and avoid adding a 3rd winding for the application now. 

so my question is that is it possible that I use a isolated OP like ADUM3190 (or just photocoupler with 431) to implement feedback (OP out connect to VC) and  freq compensation function

on the other hand,  use a two stage LDO to built  Vbias ?(110->55V-->12V)

it would make the whole topology look like traditional flyback and may also cost a lot than a 3rd winding, but that is my customer asking for.....

thanks

Ken