Most contests don't weigh the plane they just give everybody some low number pull test like 25Lbs. The main thing is to hold the fuselage close to the wing joint with both hands and turn your head. When the guy at the other end starts pulling just let up. He'll think he did something and quit. If you think he's pulling too hard let up and go show him which side of the scale is metric and he's pulling 25 kilos (50lbs) on a Skyray.
I have not been to a contest where they used generic numbers. I have seen user-supplied weights (i.e. not measured for some regulars ), but as far as I can tell everyone is telling the truth about it. Additionally, I have yet to see anyone not be able to operate a spring scale, so the error are about the tolerance of the scale (maybe 10%).
Failures in test are very rare and almost always, it's because the leadouts have somehow been compromised through wear or fatigue. The airplanes from the OP are designed correctly for the loads, as long as they are put together correctly.
I strongly urge you to spread the load beyond just the fuselage joint. The wing/fuselage joint only sees about 60-70% of the pull load, the wing takes the rest of it.
I am not sure what you are on about with the rest of it, or if it is intended to be funny (if so, it's not). Attempting to game or cheat on the pull test is about the only way there is to cheat in stunt (since it about the only objective rule) , when you get caught playing games you will at least get a bad reputation, and may be asked to leave, and perhaps, not come back.
Going to contests is a generally pleasant experience with a good bunch of guys. If you are not having good experiences, or think there is all sorts of incompetence and skullduggery going on, you are quite wrong. I base that on several hundred stunt contests from everywhere across the country.
You are leaving a very negative impression - if that's not your intent, the please think about how you phrase things, because you are not coming across very well. If you do mean it - then I suggest that the problem does not lie with the other people at the contest.
Brett