Ok, I will take a shot at it...
L52. Lots of narrow streets up there in Fieldston.
One to either L27, 37, or 38. Some tight corners in Tremont, Bedford Park/Norwood, and/or Belmont (resp.) And it could easily feed up to either Riverdale (52) or Wakefield (39) on relocation.
And maybe L29 or 49. Mott Haven and Highbridge still primarily 19th Century street grids. And access to the bridges to other boroughs.
I'm not aware of complaints from any of these companies about their rear mount manueverability. But if this discussion is about tiller's trending, why not these units?
Let the pissin' contest begin...