Wouter. to be fair the issue of exact weight is a red herring.

The box rule states only a minimum weight not maximum!.
Secondly there is a logic to not to raise exact weight. That is ratings!!
If one F16 weights 105 and another is 140kg then under the rating systems we have two separate ratings for the class!! So unless you wish to split the class only the minimum weight box needs ticking.

both of these arguments you already know..