Jackaroo 3.0 TD

I have a 08/00 3.0 TD Jackaroo which is just coming up to its 40k service. I have taken it on the beach twice since Jan 02 and have found that the clutch slips when I got back on the blacktop. The first time I was on Teewah beach towing a camper trailer however the second time (last week) I was on Moreton Island with no trailer. Most of the time I was in low range 3rd or 4th gear so as not to overtax the drive train. I bought the vehicle to use in a limited capacity as an offroader (2 or 3 times a year) and also to tow a 20 ft caravan when I retire in about two years. However if I am going to continue to have clutch problems, I will have to think again about my plans. Anybody experienced any problems with this model??