Probably, although you have to remember they're both getting something they want out of this relationship, hence why they've gone through this same routine several times now.
You know, I'm pretty certain there's a TV trope for that sort of relationship considering how much of a stereotype it is.
Although, I have no idea what it's called.
You can actually probably leave the practice action as is, since it also clarifies to Scum that you're a Vanilla role also?
25% stuck chance.
56.25% miss chance.
18.75% kill chance.
That'd be a fair way to approach things also, you wouldn't need to keep the Scum roles hidden then either.
Although, the biggest thing with Mafia setups is you need vanilla roles for Mafia roles to hide among. Otherwise you can figure out who's role is what based on role abilities instead of scum hunting.
As Jeod pointed out, the problem with this setup was actually the Conscript roles being so unique so Mafia couldn't pretend to be one of the majority roles in the game.
That'd be a good way to look at it, have to find scum by process of elimination based on who's the odd one out.
It's a far better way to balance things out, by eliminating a player as being Scum, rather than confirming that player has to be Scum.