I owned a BT50 of that model which I think was a pretty similar vehicle. I had the auto transmission and is was a great tow vehicle and would have kept it except the boat put on weight and so the auto towing capacity at 2500kg was a bit shy of what I needed, so I bought the new model in auto again only for the upgraded capacity. The boat I was towing with it was just under 2000kg and handled it easy.
I have heard on the grapevine that the manual may have been prone to the odd clutch problem for towing but that could have been driver error, hard to say.
There should be an owners forum for bt50/ranger if you haven't been there yet. I think that was where I was reading about clutch issues at some stage.