Not so much expand as make more consistent. And yeah, remove the passage. It may be simpler to just leave your area without a coin because it isn't really suited to having a hidden part. If you want to try something though, you could make it so that the second room was technically possible without the Booster 0.8, and reward them with a coin for completing it so (if you want to keep the upward-boosting part just near the end, you can give it to them before that).