Power is not an issue, I towed my D1 home on a trailer for 125 miles in HIGH range at up to 60 mph in my Td5with no issues at all !!!
to be blunt about it, imo thatlow range sh*tin the US manual imois a load of bo^^^ox!!!

 

And I would not advise using a particular gear, if its an auto use D, if its a manual drive it as you normally would, using only 1 gear will put strain on the tow vehicle when theres no need

 

But by running it in 3rd instead of 4th gear he will keep the trasmission from shifting into 3rd everytime he comes to a incline thus keeping the trans from overheating.
And remember Nick, you have a diesel, we have petrol, you have more tourqe.

 

I see your point spike, so it would be best to start in 1 and change up to 3rd once moving, if you prefer it that way. As far as torque goes buddy, the TD5 is "about" the same asthe 4.0 V8

 

Also by keeping it in 3rd you have engine braking and you keep the RPM's in the HP range so it pulls better. Just put it in 3rd and go.
I would have thought that the diesel would have more tourqe than the V8. Even with a small displacement.

 

how about weight distribution systems? we are looking at 4100 to 5000 lbs and 25-29 ft.

 

Dont bother. You are still pulling 5,000lbs. You will be fine.

 

The frame isint the weak point, its the axles/transmission. But you'll be fine.