We have also already been through why new mechanics is unneeded for Roy. He is not different enough from the non-zombie versions of Jason to justify it.
To be blunt, I want Roy in the game but he does not deserve that much time, effort, and money, to rework the game just for him (Pamela is more deserving of such but even then I'd rather have other content first) . He is a Jason impersonator just let him impersonate Jason.
I think undead Pamela from Part III would work with the current Jason mechanics. Human Pamela would be a complete rehash of the mechanics - looks unlikely.