Where are Safari Profiles stored?

I thought I was going to like Profiles but they are more of a headache to use due to their 'smart' behavior than they are worth. You can't change the 'default' and hotkey/shortcuts don't behave the same as other apps (ALT-SHIFT-CMD-<profile #> is only supported for the profile not on the active browser window.)

A "defaults read com.apple.Safari" review only shows one promising value

SafariProfilesLastActiveProfileUUIDString = "580ECC60-2ABF-4B7A-ADCB-507DAFAB64A5"

I imagine that the UUID is associated with a Safari Profile, but I have no idea where I'm likely to find that UUID.

Any ideas of where this Safari Profile information might be hidden? Ideally, I'd like to change which profile is default. Also, I'd like to be able to make a new instance of Safari start with a particular profile so I can avoid starting up Safari on my work computer using Personal profile and opening a bunch of tabs and then having to close it all and opening again after opening a Work Profile window (and vice versa for Personal Profile).