As for Spain I'd would't deny approximity to any or several wonders - it's part of their UA and therefore essential part of the game. Most likely AI Spain will not become an early runaway due to finding a wonder nor is it an instant 'I win' -button for a human. It surely does help a lot in the beginning but that's kind of the point of their UA.
I'm not sure if people forget it or not, but Spain gets 100g for finding a wonder anyway. That alone is still a good UA benefit. After doing 19 random starts with Spain with start bias enabled, I was the first to find a wonder less than 20% of the time (3 our of 19). Their wonder-based UA doesnt mean they get a first discovery every time.
This hinges on people voting Spain up to be one of the two winners though. Since there wasn't enough room to include all of the civs in the poll it will have to be voted on in these comments (see post #2 for the list of the ones that didnt make it). There is still 6 days of voting left to get them there.
Keep in mind this has to be an identical set-up and replay is infinite. Prior map knowledge isn't just allowed but required to keep results more accurate for this challenge so loading with Spain and beelining to be the first wonder discoverer creates an imbalance, imo, relative to this particular challenge.