Does not matter what the overal weight is, if you get 1.5Lbs on the nose wheel the C of G will be in the same place no matter the overal weight, think about it, put 6lbs of lead in the back, to achive 1.5lbs on the nose wheel you will need approx 12lbs of lead in the front to counterballance the load, (assuming a 2:1 ratio of distance to the C of G) you have just increased the weight of by 18lbs but still only have 1.5lbs on the nose wheel, unless it has given way under the weight.
The thing that confuses the issue is that the fulcrum (main UC) is not on the C of G, but if we think of the fus as a simple beam it starts to get a little clearer.
Mike