Do you have any suggestions for CAN and for 18F4685?
Take a look at errata.
http://ww1.microchip.com/downloads/en/DeviceDoc/80000284F.pdfSome notes:
1. There are two issues regarding CAN functionality. They have workarounds that you should implement. I doubt that microc library knows about that particular device but who knows...
2. Available silicon errata is unusually short and is only for the first A1 chip revision. I suppose xx85 series is a modified xx80 with more memory. The errata being so short you may consider as a sign that it is essentially bugfixed release or it was not very popular, and thus not well tested.
Anyway this chip is quite obsolete. Unless you specifically want to not throw away chips that could work for the good I'd consider more recent generations for new projects. Though I have no doubt that your project could be done with 18F4685, after all ten years ago Microchip targeted it for such tasks.