Slight thread drift but I've always wondered if it would be feasible to install commercial scales on the ramp such that a weight could be taken for each wheel and then converted into a more accurate Ramp Wt and CoG. Of course this could only be done once everything and everybody was on board so it would not work for planning purposes but it could certainly serve to confirm the accuracy of the pre-loading numbers and to reach more accurate speeds and flight planning figures.
It's probably been discussed and seen as cumbersome and unnecessary and I can see why.
~FRC CB