Ideas needed for a TV mount

I have a Cedar Creek 30RLBS and it has a very small area for a TV. The space between the wall and the edge of the bedroom door is not wide enough for a large TV as it is only about 26 inches. I have purchased a 42" and a wall mount that pivots 90 degrees so it can be stored vertically when not in use and it wont block the bedroom door. I need to mount the wall bracket in an open space where the TV shelf is. I need suggestions on building some kind of a frame to mount the wall mount to that will hold the weight of the TV which is about 35 lbs. The arm extends about 18 inches and is hinged in the middle at about 9 inches from each end. Fire away. Thanks