I "third" Bama, and would agree with AFD for DPI, without LOD for OPI. It works in the NFL and NCAA, it doesn't require complicated technoligy, and would reduce confusion for those not so well-versed in rules differences.
Once again, stressing the differences in maturity, physical capability, training, strategies, tactical awareness and overall objectives creates the practical and logical necessity of subtle differences between governing rules for Interscholastic level players and those participating in NCAA and NFL level competitions.
Confusion, "for those not so well-versed in rules differences." can be consistently eliminated, by those confused, simply waiting for, and subsequently being informed of and accepting the correct explanations that are presented by the game officials (of the contest they're observing).