Well, I'm not going to say it's a bad idea until I see the photos of the new one, but I will say that the current HM costume is my favorite in the park. Before Mickey's Halloween Party Disney used to have private Halloween parties for cast members only to bring their kids to the park and go trick or treating, and I worked one of those, and for that night we could wear any costume we wanted, and I picked HM. It was perfectly comfortable although the jacket was too warm for someone working behind a churro oven, but I'm sure the CM's working inside the mansion (which has a really good air conditioner) appreciate it.
Disneyland Cast Member
1996 - 1999
And what it entails would be nice as well. There was a point during the first few overlay years where I remember quite a few of the Mansion CMs doing light halloweenish makeup to more closely match the ghosts - super pale face powder, usually a light dusting on the hair to wash it out and make it a bit gray, that sort of thing.