Point foundation

Rolling resistance only needs to be overcome.

In this case, however, + slope force. Which roughly triples the whole thing. Here roughly 650 Newtons. Since the foundation is not calculated anyway, you can crudely calculate with 65 kilos slope force + rolling resistance + static friction + a bit of other stuff. (I'll leave out air resistance ;-)

So if the part "holds" 100 kilos, it fits. With the foundation size and a proper heavy-duty anchor (10-12 mm), my gut feeling says: fits easily. Whether in tension or with 90° shear force.

I am not a physicist - so I gladly accept corrections ;-)

I consider 100kg "tensile force" due to the slope to be well dimensioned. Actually, it’s less, but it’s supposed to hold anyway. Theoretically, it’s possible without it, since the brake does the same. It would still be easier to drive the caravan properly with the car right away. You can also easily get it out again by driving the car up to it again. A winch to hold it over the winter is actually nonsense. With a stand under each tire + brake, the thing won’t roll anywhere. 30cm over 6 meters is a 5% slope. Not little, if you want to sit inside. If you also want to use the caravan on-site sometimes, a more level setup might be preferable.