need a reliable AI humanizer for college essays specifically

Starting my senior thesis next semester and I want to have a reliable humanizer ready. Not for cheating but my writing style apparently triggers Turnitin even on stuff I write myself (probably because I read too much AI content and picked up patterns lol).

Requirements for my use case:
1. Must work consistently with Turnitin (not sometimes, EVERY time)
2. Needs to handle 2000+ word documents
3. Cannot change the meaning of academic arguments
4. Ideally under 5/month

I have tried the free tiers of like 5 different tools and most of them choke on anything over 500 words. Has anyone found something that handles long-form academic writing well?

I keep seeing Walter Writes and Undetectable AI mentioned. Are those actually the best two or is there something else I should look at?