How can I start sneaking out the house?

I'm 18, I shouldn't have to be sneaking out but my parents give me no freedom. I don't go anywhere with friends and I'm always with "the family". I really want to move out but my mom wants me to stay. wtf?! I even offered to pay rent and she said no. She can atleast give me some freedom if SHE wants me to live in her house. It's not like I just wont move out I actually want to! So I'm gonna start sneaking out. My room is not by the door but I have a window that's right on the porch. My dad gets ready for work at 5something so I have to leave before then. And my mom doesn't go to bed until 12 or 1. I don't usually close the door when I sleep so I guess I'll just put pillows as a body? lol.