Crossover campaigns are perfectly possible, especially with Hunter. The mechanics are compatible enough that you can make it work with a bit of houseruling. Off-hand, the two supplements which are probably most relevant are these:-

https://www.drivethrurpg.com/product...Treachery?it=1

https://www.drivethrurpg.com/product..._filtered&it=1

The primary issue is that the different splats tend to interact primarily as antagonists - this is especially true of Hunter. My first consideration would be a rationale for why...