Being that U20 is the more reputable one and requires certain criteria to be met (U23s does not, aside for age), I think it would make more sense to go the other way.
National Team Member U23 Eligible - They can claim it if they want.
U20 Trials Winner - Can request a wrestleoff against the U23s winner for the U23s spot.
I know we're playing 'backwards' there, as U23s should have better wrestlers since they have a larger pool to pull from, but those are the apples we are given to play with.