My mother never allowed me to bring girls home either, and is still against premarital sex, but I still managed to do it (with increasing numbers.)
Sometimes I would take advantage of the times she was gone, but I had a lot of "flings" in cars, at parks, random house parties, friends houses, bathrooms, random places outside (in my case, in the desert), at the river/lake, you name it.
If a girl wants to do it, she will make it happen. Just make sure it's at least somewhat secluded.
I've always wanted to have sex in one of those clear see-through elevators in Vegas. I haven't done that yet..
Edit: Just a follow up.. but remember that woman run off of emotions. Just get her into it and make the moment so "passionate" where she loses all logic and her only focus is how amazing she feels "right now" and she will fvck you anywhere.
-Scars