So would you just sign into the console with foreign account, to then see games ready to install, set it to install and then once it's on console any ID signed in can play it, hence re-sign in on main account and job done....?
Yes. You just have to set that account as Primary for that PS4. Primary is 'Home'
I have a US account but don't use it now to be honest as I game share with the same guy on Xbox so get half price games anyway.
To be honest you might just be better off waiting for deals.