Correct method of nose-weight measurement?

Hi, I am brand new to towing and going away for the first time next week.
I am trying to come up to speed PDQ, but I am having trouble with nose-weight.
Of the 3 nose-weight considerations the car is the lowest, it is C-class 220 - W204 model - 2 door Coupe, so it is "low slung" relative to the caravan. The manual says 75Kg, but Practical Caravan says 75g to 100kg.
The first time I measured the caravan nose weight (on level ground), by putting the scale under the hitch socket and lowered the jockey wheel until the scale stop moving and it was above the 100kg, so I moved some stuff to the boot and and some to the back of the caravan (as a counterweight), this brought it down to 87kg, but it means I cant really carry anything else and we have not even tried packing our clothes or food or anything. Despite this I have been out for a couple of practice tows on local roads I know well.
After thinking about it for a couple of days, I have convinced myself I must be measuring it incorrectly because by just lowering the jockey wheel as far as it will go, the hitch is actually quite a lot lower than the height of the tow-ball on the car. So today, with out changing the contents or re-distributing the weight, I brought the car up close enough to the caravan to place a spirit level on the top of the tow-ball and the tow hitch. I then lowered the jockey wheel until the Spirit level was level. I am hoping this means that I am measuring the actual nose-weight that will be exerted on the car. The measure was less than 50kg, which I am guessing is too light.
My questions are :-

Am I now correctly measuring nose-weight?
If so, should I keep the weight at 50kg or is it better to have the heavier 75kg?
Will a heavier nose-weight help dampen/suppress the bouncing effect on my rear suspension because it makes me feel sea-sick?

Many thanks to all who are able to reply.