I know nothing about Rherras but if he signs and is an attacking type full back I could see us playing with a back 3 next season with him and Paterson, if he stays, as wing backs.
I think Neilson may have hinted at that previously but I can't remember where or when.
We do seem to be going in the right direction though if it is a 3-5-2 system we're after with the signings we've been linked with. New strikers, a left back and an attacking midfielder are the additions that last seasons team need to play that way.