I'm seeing a lot of ngons in your lowpoly model. Some of the stuff you have modeled could be baked but not much. Clean up the topology and do a pass on your hp to soften it up a bit and no doubt the bakes will come out excellent.
The guy claims using ngons saves on your tri count when everything gets tessellated anyways. but do whatever you want, just trying to help. you seem to be working very hard to justify not taking a few minutes to connect edges on your mesh in an optimized way. A low-to-high workflow relies on keeping the ngons intact,…
Choosing to auto-triangulate a mesh full of ngons can give you unpredictable results, both causing random instances of faces overlapping. At the very least, its a lazy and inefficient way of optimizing your lowpoly model. It's going to only take you a few moments to draw in edges, best to actually control optimization and…