You are advocating to take an unprecise starting point
In what way is a local VOR fix "unprecise"?
apply an even more unprecise methode
In what way is tracking information from a Dual IRS not precise?
to find a point that ATC expects you to overfly with great accuracy.
What part of
"The phrase "Negative RNAV" is appended to each radio message on initial contact with each ATC frequency change." do you or ATC not understand?