How to fly with mannequin legs

I am flying home with half a mannequin. Yes, that's right. The bottom half. The problem is that the dimensions of the legs and pelvis are such that the custom box I am making for them will have to be an inch or two over the 62 linear inch limit. I don't know if the box is narrower on the foot end if that would help. My other idea was to put them in a golf bag but thought that probably wouldn't work. Any ideas? How strict are the gate agent's measurements going to be? I want to avoid the oversized baggage fee!