Thx to all the suggestions - I'l be contacting some of you soon. 

The backstory:
I had sucessfully and slowly towed a friend's 22 foot boat in the past. They had accompanied me with it, and had also driven Cunegonde many other times, also successfully. 
Unfortunately this time the boat has been in storage all winter. It did not occur to the owner that the boat should have been checked for cover water leaks, and how much water might be in the bilge.
It turned out that the boat had about 4 tons of extra water. Concentrated forward near the tongue of the trailer . While attempting to move it, they revved the van engine very high in first gear,and used the clutch very... creatively. Neither my clutch nor my receiver hitch was very happy about any of this.
And this, my friends, is why I need to have the clutch looked at. And why yet again I get a lesson about not loaning my van to anyone doesn't own one themselves. Even if they also own an older Volkswagen bus.