The GPS 175 displays on the PFD. If you replace the MFD with the GPS175, power budget isn’t a problem. If you keep the MFD, the easiest location is to mount it is directly under the PFD. You will need to use it for selecting procedures and modifying flight plans. I believe that location still meets the definition for proper field of view.
A search on VAF has a lot of information regarding the power budget. I believe the second screen that you added depleted the remaining power available from the alternator. The Ducati voltage regulator is prone to failures. A HS VR replacement kit is available from Van’s but, IMO you are still going to be over the power budget.
In case of a power failure you will not have the reserve needed to satisfy the power reserve requirements for an IFR installation. The GPS 175 only has a single power source. You could give it pass through power from a TWC back up power supply. The current TWC is not big enough to handle the load/time required. I believe you will need to up size it.
All said, this is your plane. Build it as you wish but, please be safe.