Commissioned GP coverage is usually only ten miles, so 4500 above the facility is technically a no-go. Most equipment will pick it up even if it is below the tolerance signal levels, but the facility isn't approved further out and there are no guarantees. You should get flag warnings if it is not to be trusted...
There are GP "back courses". They usually aren't anything you could approve as a GP, but if you are approaching the reciprocal runway with the ILS tuned, you may pick one up and see it on the needle... with no flag. They could be perfectly flyable and lead you straight to the departure end of the runway.
The procedure designers with all the expensive training are the ones who are allowed to be creative in this case.