№ numero / tracking

I’d like to be able to apply tracking to the parts of my № numero sign;
therefore I created a separate glyph called »numeroPart« for the right half of my numero design, and put following code into the ordn feature:
sub N o' period' by numeroPart;
As far as I can see this works as expected, and I believe text including this can be copy/pasted into other typefaces without problems, because what is copied is still N o period, not my custom glyph.
Are there any downsides on this strategy that I’m not aware of?

Call it o_period.numero, otherwise no complaints.

Thank you!