What about two tiers (similar to a Challenger save in the XOTMs) but on a much bigger degree, i.e. Victory-Condition-wise à la SGOTM.
For example, a team that thinks that they are "the awesome" plays for UN Diplo while other teams play for Apostolic Palace Diplo. We'd still get comparisons between the games, since a lot the same strategies can be used (they are both Diplo games) but the AP Diplo games have a competitive advantage in that they can theoretically beat the UN Diplo games, time-wise.
However, the Laurels are NOT tiered, just like in any game where we have multiple Victory Conditions. In this game, there is only one type of Victory Condition that can be used for winning (or perhaps the backup winning condition is shared by all teams, such as Space) and your team must decide which one of the two primary Victory Conditions that it will target before the game begins... if they happen to win the type that they did not choose, then they "lose" just as much as if they had "won" the game via a Domination Victory and thereby "lose."
The teams that take the "Challenger" version are decided completely on a voluntary basis but we use community peer pressure to encourage "stacked teams" to play the Challenger game or else get mocked by everyone else.
We'd also play with identical starting saved games, so there isn't concern about divergence due to map differences... just different chosen Victory Conditions stated before the game starts (with, as I said, possibly having the same "backup" Victory Condition for all teams).
Or, we could loosen it up a little bit, in case the concern is that an AP Victory might actually not be easy to pull off on the map... meaning that a non-Challenger game can win via AP Diplo OR UN Diplo, while the "Challenger" teams can ONLY win via UN Diplo (and the "Challenger" teams would "lose" if they won via an AP Diplo Victory). That way, if the map somehow proves to be too tough for an AP Diplo Victory, at least every team will still have the chance to compete for a regular UN Diplo Victory.