I"m not sure why the "radar vectors" are required since the controller
doesn't need to read you a heading. Just ask for direct to foobar, if
you get it, fly direct foobar. If the FAA asks you how you navigated
there just tell them you were taking star shots like a pirate, it
really doesn't make a difference. There are lots of stories of military
and commercial pilots (not even too far back) that would fly direct in
IMC just using a wizwheel. Nothing prevents that today.

-Robert