If you're hiding it you shouldn't be doing it. He's going to see that youre willing to lie and sneak around to see him, your not that trusting. I want to be the cool guy and tell you to go for it, but the impression your giving is that your easy to fool to get what he wants. Dont set yourself up for heartbreak and a bad rep. You wanna be the chick they CANT get to- that's how you stay in control and get what you want.
He is doing things he should not and thinks he needs to hide it. You need to ask yourself if what he wants to do is good for you or can it get you into big trouble. Not just with your parents, but pregnant or something worse.