Idk how to make a mod menu, sorry I'm not that good at coding
I think the mod menu is not very compatible with this mod. You would have to move the original Assembly-CSharp to a new folder in Managed, open that ith dnspy, move the mod menu to where the original CSharp script used to be and open the mod menu in dnspy. Then look at what scripts are different in the - namespace. It will require even more knowlage than I have in coding, which is less than basic, to add a character settings page for ghost Baldi, or you can just change the referrance from "Baldi" to the new ghost character's name in \-\PlayerScript\OnTriggerEnter that doesn't say "Baldi". I think only normal angry Baldi can be controlled by that page by default.