Isn't there a rule that FM translator for AM 60 dBu contour is contained within the greater of the 2 mV/m contour of the AM station, or a 25-mile radius centered on the AM station’s transmitter site.The translator coverage is not dependent on the AM coverage.
A translator could have its 60 dBu coverage anywhere within a 25-mile radius of the AM site.
But - WIBC would have to find an existing translator to buy. The FCC windows for new translators came and went a few years ago.
If you have really good AM signal, could you go past the 25 mile limit assuming there you don't interfere with an existing operation?