gonna post the config i arrived on to get this working to save other folks the trial and error - i've added clickers and shamblers to a lot of the base groups of zombies that can spawn, and the bloaters to InfectedArmyHard which was honestly a terrible idea because they're incredibly powerful lmao. from experience they can take like, 6-7 headshots from a .308 before they go down.

also because i have a stupid sense of humor i made it so they all drop mushrooms and guts/human steaks as loot

you need to change the following files for this to work (assuming default directory names and structure for this):

mpmissions/dayzOffline.chernarusplus/db/events.xml
mpmissions/dayzOffline.chernarusplus/db/types.xml
mpmissions/dayzOffline.chernarusplus/cfgrandompresets.xml
mpmissions/dayzOffline.chernarusplus/cfgspawnabletypes.xml

haven't tested it but i'm pretty sure you really only need to change the last 3 to get them to drop loot

here's a link[github.com] to the diff in my personal github for my dayz server config that implements all of this:

high level this just creates a preset in cfgrandompresets that describes the loot i want them to drop
cfgspawnabletypes specifies which mutants can drop which loot (bloaters can drop more, etc)
the changes in events.xml just designates which types of zombie groups they spawn with and at what probability relative to the other types (i set it kind of high because i was trying to see if this was working at all)

it's not in this diff but you just need to add entries in types.xml for each mutant, something like