Yeap, you should not play with alcohol and driving... But you could keep in mind that the body can break down 20ml of pure alcohol per hour, meaning that one 50 ml glass of whiskey will be completely gone from your system within one hour from drinking it... I have tried it a few times and always worked... I mean being stopped by the cops, being breathalysed and ZERO alcohol... Should hydrate plentifully and this can't fail... or you could stick to energy drinks or water and drive... consider the car as your portable bedroom...
Coming back to your situation, I have pulled a chick that I work with from a nightclub in a taxi, simply giving the driver my address. She said nothing, we arrived at my place, went up without talking about where, why and what, had sex and then called her a taxi to go home... You could try that, success lies in the delivery... confidence will get her to follow you without asking any questions...
And finally, make the call cell to cell, it's more personal and she can take the call to the corridor instead of being tied to the desk...