[jacobobryant]

It's hard to say for sure without having first-hand experience with the code base. But rewriting messy projects from scratch is often a pitfall, and I would be very cautious about taking that route (especially given "I feel that I'm in way over my head" and "I feel competent enough in ... but not in creating a feasible architecture"). The last thing you want is to spend months creating a new project that ends up being not much better than what you started with, a scenario that happens all too frequently.

I would consider using this as an opportunity to learn and refactor a large code base. That's an extremely valuable skill, and it's hard to get it without situations like these (whereas anyone can get practice creating a new project on the weekend). You might have to spend a lot of time staring at the code, feeling like you're not making much progress, but it'll (hopefully) be worth it.

On the other hand, it is possible that the code base is just horrible and should be nuked, so use your own judgment :).