As of right now, there's no current way to have the vehicle limit above 224. Something about modifying the .exe of the program, and that being illegal. I mean, I'd love to be able to have more than 224 vehicles, and more than 3,000 files/.dat. But as of right now, there's no current workaround. Maybe with OpenLoco, but they haven't figured it out either.
I don't expect that they'll figure it out at all without rewriting the game from scratch like with OpenTTD. OpenRCT2 has been in development with constant patches and it hasn't gotten rid of that limit either.