"zero" versus "oscar" versus "sierra"

I fly an airplane whose last two digits in its identifier are "0P"
(indicating that it's an OurPlane aircraft). Of course, OurPlane would
have liked it to be "OP" instead, but the FAA won't allow "oscar" in
aircraft identifiers, only "zero".

It happens that there's another airplane at my airport with the exact
same identifier identifier except that it ends in "SP". In the air it
turns out that "zero poppa" and "sierra poppa" sound an awful lot alike
(try it), which has occasionally led to confusion when both planes are
in the pattern. (I've taken to saying a very exaggerated version of
ZEEEEEE-ROW-OOOO when I'm flying.) Allowing "zero poppa" to be "oscar
poppa" instead would alleviate this confusion. Does anyone know what it
would take to try to make this case to the FAA to try to get them to
change their minds?

rg