Combination of a hilly area and a 24ft boat would rule out any cars for me, don't know why people suggesting them....its easy to say 'x' car tows great, but I'd want to be legal/safe. Plus, we scrabbled for grip for years with front wheel drive family cars and just an 18ft speed boat, and its hard on clutch too, whereas any jeep I had was effortless by comparison - sounds like he's been there before and seen the difference.
Any old full size 4x4 at £3,000 nowadays can be very hit and miss due to the life they live - fine if you know what your looking at, but bit of a gamble IMO. Providing the boat isn't over-weighting it (assume was fine with the Tuscan) I'd probably avoid the Shogun/Disco/Trooper idea and go for a CRV/Rav4 size of a thing, though they have no low box. A Grand Vitara has a low box and Peugeot HDI engine. A 2.8 Cherokee has an absolute ball of torque, low box, and a higher towing cap of anything else its size (2800kg I think), they're cheap too so your budget would pick up a tidy one, though not as reliable as the jap stuff. I'd avoid Patrols/Terranos, they like to rust like nothing else, and the 2.2 in the Xtrail is a Renault engine (although I've had a few with no bother) the idea of steep inclines/heavy loads/short runs would worry me.
I've my discovery up for 2195. 02, td5, low box if you need it, drives pretty good. In budget and capable and not rotten.Fixed the Tuscon. New turbo, intercooler and a few other things. Hes still on the look out for a replacement though.
A friend would use his wife's cherokee for towing now and again, lifting bags of grain, when she's not towing her horses around.
I'm pretty sure the tri-axle trailer he uses will take 3 bags of grain and the new hilux he has access to struggles, whereas his aging jeep does it effortlessly. To the extent he rarely uses the Toyota and free diesel when doing grain runs.