OP, this is simply a problem with the Surface having the kickstand rather than the traditional joint between the keyboard and screen areas. I've had the same problem as you. A couple of things I do that I've found help:

• Don't use the tray, just put it on your lap in a way that works
• If using the table, use it at a slight angle so you can push it a bit farther away without the kickstand falling off the back