EDIT: Issue resolved. I rebooted my PC and very briefly set the in-game fps limiter to 30 fps and never experienced the crash again. Thankfully, I was able to turn the limiter off immediately upon passing the point at which the game kept crashing. Playing this game at 30 fps rather than 60-80 fps would have been very disappointing. If anyone else runs into an issue like this, hopefully this helps somehow.

I assume this is happening because while I was exploring randomly the other day, I happened upon what I didn't know would be the final mission area. I fought all of the Stalkers, then proceeded up the mountain where I encountered a cut scene and a Stormbird. I killed the Stormbird and kept going forward. I made it into the very beginning of the ruins but could not proceed further, so I left.

Now, I have progressed to the final mission in the game and when I go through the area leading up to Gaia Prime, there are no Stalkers, no Stormbird and the game crashes every time I reach the same point, roughly 200 meters or so from the objective marker. I've reloaded the save several times and it crashes at the same location every time, just before I arrive at Gaia Prime. It's quite frustrating. I had only experienced 2 crashes before this and they occurred at random times in my 60 hours of playing. It's such a bummer that I can't finish the game because of this bug.