If you are worried about your friend seeing you, pick up a girl, and go to Motel Eden. It is a short term motel, very nice rooms, jacuzzi's, etc. Something like $35. B/C if you are worried about your friend, and even if your chica is not wearing a skirt, not showing cleavage, and is not banned, it is very very very easy for your friend to bump into you with said chica. Could be in the lobby, elevator, he could be at the bar and see you walk in with her, he could be strolling around the hotel, on the computer, etc.
Most easily, if his room is near yours, hearing that click clack of the chica's heals, and they are loud, he may be compelled to look out the peephole and what does he see?
I remember I was on a business trip with a very reputable person i our community. The same thing happened, his room was a few rooms down from mine, I heard the heels, looked out, and out came a very fine escort out of his room. I was shocked, and never told him what I saw

Then again, unlike your friend, I understand the guy's code.
PURA VIDA!