There is a way to get a SPDT switch with "off" --sorta. They make the
double switches that fit in a single box and use the same cover as a
receptacle, though I forget the exact name of them. You can get them
with one switch being a 3 way or both. If you use one with one regular
and one 3 way (SPDT) you can use the regular switch for off-on and the 3
way for what you are wanting to do. Larry