Survival Route proof of concept.
Notes:
Everything up to the first Heart can be played normally. The early Great on that hold before it was a mistake.
The trick is mostly just early holds. Max scoring is just minimizing how many you need and routing around Greats.
The masher can be completed for full points, but it's easier to just let it play out for a proof of concept. The key is to get the final hit around the same time its timer naturally expires.
Overlapping holds is important to maintain HP. So, near the end, any time a hold crosses over another it can be hit with an Early Perfect instead of a Great for more score.