Oh yeah, that's not a bad idea and definitely what I'd do if I was bootstrapping a bunch of hosts at once. As it is I set up maybe one new host a year, which means that it's at least as much work to rebuild an installer boot media + my config as it is to do a base install and then pipe a script through bash to finish setup.
It should be relatively straightforward to also mount /home from a separate USB stick partition, but I haven't tried.