Not quite. I'm imagining two independent arms, probably placed at opposite corners. They'd have one servo for rotation along a 90 degree angle, and another mech

Not quite. I'm imagining two independent arms, probably placed at opposite corners. They'd have one servo for rotation along a 90 degree angle, and another mechanism for extending or retracting it. I can't really draw something at the moment to illustrate what I mean. (But practically, yeah, what you linked is probably what would be required, otherwise I don't know if it could support it own weight.)