Help! Classification regulations for 103m yacht for charter..

Warm greetings to all.

I represent a party that acquired a 103m yacht (gross registered tonnage 4633 tons, net registered tonnage 1389, overnight accommodation for 39 crew and 25 guests) two years ago and endeavored to make the yacht ready for international yacht charter to use in the Med and worldwide.

The yacht was previously registered as a private yacht and the new owner whom I now represent went to great expense to convert her classification to Passenger Ship. This was done under the advice and management of a company which I suspect may have knowingly or unknowingly unnecessarily cost the owner several hundred thousand dollars' worth of modifications to meet Passenger Ship classification requirements.

I have now been asked to assess the situation and offer recommendations.

However, before I jump to conclusions, I wanted to know the following:
Is there any real reason, in the sense of mandatory regulations, that required the conversion of the yacht to a passenger ship instead of just a commercial charter yacht to allow the vessel to operate charters say in the Med?
I called one of my friends at Camper & Nicholsons charter division and he told me that a commercially registered foreign-flagged yacht is free to charter in the Med. Nevertheless, I suspect maybe the vessel size/guest capacity may not allow it to be classified as a commercial yacht but only as a passenger ship?

Wouldn't it be better operationally to change the license of the vessel and classification to commercially registered yacht, to escape the stringent requirements of Passenger Ship classification renewal, more expensive berthing charges, etc.? Are there any obvious operational advantages/disadvantages to argue for the classification and registration of the vessel one way or the other?

The help of any knowledgeable fellow seafarer in enlightening me on the issue and pertinent classification requirements/restrictions for a vessel of this size vis a vis charter requirements would be greatly appreciated.

Best regards,

Ali Badawy
P.S. you may kindly reply directly to my email alibadawy@gmail.com or here. Thank you.