Correct method of nose-weight measurement?

While moving my twin axle 1800 kg caravan with the motor mover it is not uncommon to have the jockey wheel lift completely off the ground when passing over a slight inclination. This is with a static level nose weight of about 95kg.

From this I infer that the same happens when towing, and also in the opposite sense that the nose weight increases, all with a relatively small slope.

I would advise the OP to sort out the "low slung" problem as his outfit will never tow satisfactorily rigged as a downhill racer.

 I have often thought that is where the Max tow bar capacity, cannot be, it seems adhered to when on most roads there is the undulations that must surely give a higher and lower reading and on the towbar than when static   ,

If you ever have the misfortune for the jockey wheel to fail and the hitch to slide to the ground, you will soon realise that noseweight increases as the front lowers.

I came across a couple that was in that predicament about 5 years back. I asked  if they wanted help and they did. They were surprised when I said my arthritis precludes my helping you to lift but, with your permission I shall stand in your rear bathroom close to the wall (I am pretty lightweight ). They no longer struggled.

The dynamics will apply similarly to all tow cars, and to all trailers, so the manufacturers will, I trust, do their calculations of the maximum loadings that can be withstood on a frequent basis and express the result as a figure that can be easily measured by users. 

This will be nowhere near the maximum "fail" loading for the arrangement. I recall a demonstration of the tow point strength of the Discovery 3 when it was introduced where one was hoisted by crane using the front tow point, and a lifting beam was attached to the rear tow point which supported another three Discoverys. At close to three tons in those days that was over eight tons at least on the rear tow point!  Land Rover rate it for use at up to 150 kg.

Over the years I have had the jockey wheel clamp slip down the jockey wheel a few times and yes, the easy lift fix is to ask someone to simply stand in the bathroom at the rear. 

I park up in my drive, without lowering the corner steadies. On occasion, two of us have gone in and two of us go in the bathroom - I have had the caravan tilt over, nose up. Something to be aware of.  

On a recent expedition the girl friend was doing the first bit of moving the caravan from it's nose-in position to get off a pitch while I positioned the Land Rover. The jockey wheel inadvertently fell into a bottomless rabbit hole, from which the motor mover was powerless to extract it.

She was concerned that she had done something really terrible when I sent her to stand in the rear washroom, but all became clear as the mover could then do what it is supposed to.

I would worry about balancing the caravan by putting 'stuff' at the back to lighten the nose weight. Physics, and 'moment of inertia' means that a given weight will have more effect the further from the pivot, (in this case the hitch). Weight at the back is more liable to provoke side to side snaking. That is quite frightening, and not many cars have the quick power availability to pull out of it. Just my 1€ worth.

We had an end kitchen van at one point and it was the most unstable c/van we ever had ,no matter what we tried 

I would worry too. No one was suggesting moving weight to the rear for actually towing the caravan, just to transfer weight temporarily to the rear, to make the nose liftable in the event the jockey wheel slipped in the clamp, or there was some other issue.

My loading of the rear end is limited to my plastic step and the Waterhog, which both travel on the floor of our shower, plus a small sealed container of drinking water - just in case.

My awning and folding chairs sit on the floor, directly over the axle. TV towards the rear of the seating at the front. Anything of any weight, is removed from the high lockers, all tinned food transferred to the floor of lockers and no containers are allowed to be partially filled with liquid. To set the nose weight, I simply move the awning back or forward along the 'corridor'.

Long ago, I was a passenger in a car towing a caravan down a hill, where the caravan began snaking and eventually turned over, lifting the rear of the car up in the air via the tow ball. Fun it was not, but it made me extremely wary of what can happen if you do get things wrong.

Pre-the Alko built in damping, I always used one of the spring types and would (on an empty road) deliberately provoke a snake, where I knew I could easily get out of it.

I scoffed originally scoffed at how effective the Alko might be for years, until I bought a caravan fitted with one. I don't scoff any more - Having spent quite a few years towing with one and deliberately trying to provoke a snake, I have never managed even a slight one. I even took my fully loaded outfit on a test track, towing at 90 with absolutely no issues. 

Prior to the Alko I would always feel the sideways push when over taking, or being over taken by large slab fronted vehicles and have to grip the steering tight to respond to them. I no longer even know they are there, except by seeing them in my mirrors.