If your 37 is the same as my old 2001 model, don't think there is room aft of the water tank so the tank would have to be removed. That was the conclusion I came to when I investigated before I sold the boat. The newer Farr designs like Ripster,s 36 and my 33 have different shaped bow sections which means the tank is further forward and the thruster is indeed aft of the tank.
Any particular reason for a Vetus? as Sidepower are more commonly fitted to Bavarias - original equipment for many years.