I repeat -
Don't forget linux/unix is a multiuser system, once installed, an application should be usable by every user, including ones who did not exist when the application was first installed.
Packages such as debs should not mess around in user space ! Unix systems have all sorts of 'users' installed that are not real users and you risk the wrath of a leather winged dragon from hell if you mess around with their accounts. Its the wrong thing to do.
Its very, very easy to make your app prepare the end user env at first start up -
Does config file exist ?
Yes - read it and use it.
No - create a default config file
Davo