There’s no means of handling an “air gap” between a particle system and a culling object. If I set the “Invert-Cull Inside” on, I can use the culling object to remove the particles where they would be inside the mesh, but if wanted to also cull all the particles within 2 units of the surface on the OUTSIDE of it, I can’t. So I’m wondering if it would be possible to allow for a negative Culling Distance to allow for cases like that without breaking the current setup. In cases where Invert-Cull Inside is off, the negative Culling Distance would “pad” a film of particles over the surface of the mesh.
I will leave it to Darcy to decide if it is technically feasible.
It is kind of doable using the (un)Signed Distance from Nearest Point operator in MagmaFlow so it might not be the highest priority.
But if it is easy to implement, I would be all for it since it would be simpler for the end user. 
Yeah, that’s what I did end up with, which is what made me think it might be possible in the base object.
I would be nice though if the signed distance operator was signed. It’s been one of those things I have to deal with at least once a week.