It's looking nice Ollie. I do have one concern though.
I think you might need to do some work on the complexity of the 3Ds. If your PC struggles and even crashes when displaying it in the sim then I've got a feeling it's going to do the same to other people.
Now, you may have a **** PC, but you can't assume everyone has high end machines. This ride will fail miserably if no-one can view it smoothly on NL. I think that would be a huge shame, you've put a massive amount of effort into this project and I think it looks fantastic. I just hope it doesn't all come crashing down on you at the last hurdle.
Now, I don't really know what to suggest to be honest. I don't really know enough about 3Ds to give much help, but from the stuff I do in AE I do know that poly-counts and complexity where it's not needed doesn't ever help. I don't know, I just don't want to see you, or this, fail.