Q: My biggest thing is categories. That's the biggest thing holding me up right now. Like if I make a 2015-20 Mustang bucket, can you click that then click clutches. Etc.

A: Yes, the buckets can provide collections like "2015-20 Mustang Bucket". From there you could use a plugin to provide other search details and navigation. Fitment search is also another way to fill the gap. Alternatively you can simply use the fitment based collection as a collection link in the native page editor.