How about this.........give the "best of" the G5 a conditional bid into an 8 team playoff and see what happens? It takes time for trends to develop (we really don't even have enough data to make a ton of conclusions on a 4 team playoff yet, to be honest). Let's say that after 6 years, the G5 team has yet to advance(assuming a qualifier every year, which is probably a stretch) and they are routinely getting smoked. Cool. They get the boot, or more strict conditions.
While I admit that its impossible to make it truly fair, I don't think its fair to entirely discredit them.