How can I get alone time with my boyfriend?

We both still live at home and it's summer. His mom works at home and he has a little sister so they are at his house all day long. I come over, but we can't really have any fun time (No, I do not mean ). One time she left us home while she picked up something from the store so we got some alone time and before that, we had to snuggle at the park -__- My dad works out of the house but my mom is a teacher and is also on summer vacation but she is usually out of the house doing things. He wants to come over since my parents aren't home but I'm nervous letting him. It's because I know if my parents were to randomly come home (which they do allll the time as well as my older brother) I would completely lose all the trust they have in me. Should I let him come over anyway though? I don't get anytime to be with him alone and he is about to leave for the army in a month so after that I won't ever get snuggle time. ): How/where can we get alone time together?