I think the female guide concept is fantastic and I would have used one in many cities I've visited for the first or fifth time.
That she couldn't get into every venue is not an issue. Would I want a male guide sitting with me in an oppai pub giving me advice on how to suck a nipple?
She can still tell you which places are what you're looking for, make suggestions you didn't know existed, walk you to the street, floor, door ..., translate with the tencho and vouch for you. She can tell you the rules of the particular club/soapland/whatever and tell you what to expect and what to pay. Then an hour later you meet up again (or she just goes home). When I have normal guides they don't stay with me for my $100 meal or walk me through every show, exhibit or shop, they often bugger off alone or hang out in the car/van and we all prefer that.
Places like [Redacted] charge a hefty premium for acting as a baka gaijin concierge. A female guide could perform the same service of booking with a normal Japanese service (for cheaper), walk you to your love hotel and call them back to finalize the deal. All for less than [Redacted] charges.
IME, female guides are far preferable to male because, again IME, they are just more pleasant, less bossy, more playful and tolerant of my weak language skills. Except for the bossy middle aged female tour guide I had in Prague, but that was kind of hot in a weird way too.