I have no experience with electric motors..but have plenty experience using a small auxiliary engine for slow lure trawling.. or if Im just puttering around on a nice day..saving fuel and loud noise from the bigger main engine.
As lightning said...its not a problem. It will make the boat slightly “crab” along..and the further the engine is from the centre line..the more it will crab..but its hardly noticeable if you keep it as central as is reasonably practical.
You have two options to steer the boat..and I use both at times.. mood dependant and for no other reason.
Method one.. raise the main engine to reduce drag..and steer with the running auxiliary engine.
Method two .. secure the auxiliary engine so it doesn’t turn to steer and only pushes the boat.. then use the lowered main engine as a rudder to steer the boat.
Not much else that I can add. ..its certainly not a problem in practice ... assuming you have space for the engine