I don't think civics should be part of the test. If I understand the point of OP , it's a true demonstration of the silliness of scaling cost. All techs zero civics is a better setup imho.
If you're stretching that far, however, the only point you're making is your own silliness. You'd just be making a case
exactly so that it looks as badly as possible.
But if you're doing it this way - it's going to be a lot harder because you lack walls, however, your city (I assume) will still have a high defense strength, and 30 strength difference = instakill, so no one would be able to assault you either way, allowing you to start with a builder. After that, you start working on a Commercial Hub and you chop three forests, thereby finishing it (remember, a chop always gives a third of the district cost). Next, you build a settler, put a second city down, and start building a builder in that city, while your first city continues with the next settler. Simply said, you just keep using the "chop three forests to build a district" tactic, while you don't need to build military units because your cities have high defense strength. If needed, you can even put some walls in there in between; if you rush walls from turn 1, you probably have them up in 10-15 turns (normal speed), so then you are guarateed safe.
Also, I don't know how Firetuner works, but I actually kinda wanna try it out, so can someone give me an initial save with all techs (but not civics) completed? With initial, I mean that I can still move both my settler and my warrior. Civ doesn't matter, though I'd prefer not France because France.