Gyro 
Piaow Birb!
Luna was recently complaining about how everybody uses Derpi or e621 rating guidelines, but I think you find that the problem lies in the fact questionable implies fetishy or softcore porn without genitals in common parlance.
Genitals themselves on most sites are classified as Explicit, or if there's a lower category, Mature. The confusion here comes from using the term questionable, rather than mature, and I think you're going to have an uphill battle teaching new users that questionable actually means mature on this site.
Mature:
Deviant Art, Furaffinity, furrific, Furrylife, FurryNetwork, Weasyl, Ink Bunny, ESRB
Explicit:
Derpibooru, e621, tumblr, Patreon, Sofurry, MPAA
ONLY Derpi and e621 have a rating named 'questionable,' and those do not allow content with exposed genitals.
With all this in mind, while I agree that you dont want to be E621 or Derpi, I just think that it'll be easier to do this adjustment right now while its small, rather than having to fight this through the entirety of your time here.
Genitals themselves on most sites are classified as Explicit, or if there's a lower category, Mature. The confusion here comes from using the term questionable, rather than mature, and I think you're going to have an uphill battle teaching new users that questionable actually means mature on this site.
Mature:
Deviant Art, Furaffinity, furrific, Furrylife, FurryNetwork, Weasyl, Ink Bunny, ESRB
Explicit:
Derpibooru, e621, tumblr, Patreon, Sofurry, MPAA
ONLY Derpi and e621 have a rating named 'questionable,' and those do not allow content with exposed genitals.
With all this in mind, while I agree that you dont want to be E621 or Derpi, I just think that it'll be easier to do this adjustment right now while its small, rather than having to fight this through the entirety of your time here.