There was money left on the table during Missy's prime in regard to touring, but I don't really remember any female rappers doing any big tours besides Lauryn Hill.
In 1998, Missy headlining or co-headlining a "Ladies Night" tour with Lil' Kim, Da Brat, Total and Aaliyah with Timbaland & Magoo and Nicole Wray as special guests could've been big considering they all some sizable hits in 1997 and 1998. Missy was killing 1997 with her own songs and features on Kim's "Ladies Night", SWV's "Can We", Total's "What About Us", and Timbaland & Magoo's "Up Jumps Da Boogie".
In 2000, she could've done a "Real World Tour" featuring Ginuwine, Aaliyah, and Lil' Mo. I could imagine how lit it would've been to have Nas, Eve, and Q Tip join her and Lil Mo to close out a show or shows with the "Hot Boyz" remix or Mariah and Brat cone out for the "Heartbreaker" remix.
In 2002, at the height of her popularity, she could've headlined a tour without really having other acts on the bill. She could've maybe done a joint tour with Luda. At this point in her career, she was popular enough and had enough material without needing other acts.