Hi Dusty,
My comment may need some more detailed explanation;
With most single axle vans if you raise the jockey wheel, the nose will tip forward and touch the ground. In other words there is positive nose load, but as has been explained in other older threads, the actual nose load changes depending on the height of the hitch. In fact in some instances, if you lift a hitch fully up so the tail of the caravan sits on the ground, some caravans will actually stay in that attitude - the nose load has reduced and may have actually turned negative so it is lifting.
This fundamentally why setting the correct nose load must be done with the hitch at the same height from the ground as when it is attached to the tow vehicle in a fully loaded and ready to tow condition. With a TA the change in actual nose load is comparatively slow compared to hitch height.
This is all due to the fact that to achieve a positive nose load you have to arrange the item in a caravan so its centre of gravity is a little forward of the main axle.
The situation is the reverse with a Twin axle. The CofG will normally sit between the two axles. This can be shown by raising the jockey wheel, and finding that the hitch does not fall to the floor but hovers at some height. You have to actually push it down to make it go to the floor, but remove the pressure and it will naturally rise, equally you will find that you have to apply a lot of force (compared to an SA) to lift the hitch from its resting height. The transfer from negative to positive and back again occurs over a very small height change.
For this reason the nose load must be adjusted with the hitch at the same height as when the fully loaded caravan is hitched to the car. Small height differences may have a big effect on the actual nose load.
That is why it is so critical with a TA to set the nose load correctly.