"Pilotboy, I enjoyed our conversation last night, but having had some quiet reflection time, I don't think we would be a good match. I wish you well on your journey!"
Send it through the email - use the one provided by the dating site if that is all you have - don't text, don't answer the phone.
Anyone who pushes you to meet that quickly, tell them that you'd like to get to know them a bit better first, so you have something to talk about. Honestly, if they push about ANYthing, run, don't walk, away. No way to start any kind of relationship. Remember, when you first meet people, you are teaching each other how you want to be treated. NEVER say yes to something that you don't want to do!