The answer was easy. Once it was found!
On the server side (and can do same on client side) you can access the static object – NetworkComms. It contains application wide settings and defaults. Not shown anywhere in tutorials or documentation, but it works. So:
SendReceiveOptions nullCompressionSRO = new SendReceiveOptions(DPSManager.GetDataSerializer<ProtobufSerializer>(),null,null);
NetworkComms.DefaultSendReceiveOptions = nullCompressionSRO;