Longer term boat hire in France

[starman]

I have friends in the USA who are thinking of a Covid permitting 8 - 12 week boating trip to mainland Europe next year. 
They want to rent a three cabin boat so visitors can join them along the way. 
They’ve looked at prices from the main hire operators and obviously it’s no cheap trip for that length of time so they are wondering if there are any direct from owner hire options. 
Anyone have any knowledge of the European scene? 

[Dav and Pen]

There was possible is a man who hires out his small barge to long term visitors. His Facebook site appears to be dead at present but I will make enquirers to see if there is a way of tracking him down.