I know there was a guy who made a full scale Elite costume. His legs were solid hard foam, I'm pretty sure. Or if they weren't, then he built the foam around the stilts. I'm pretty sure that you'd want to do foam just because of the weight, or at least a good portion.
If you could use animatronics, or at least a pulley system group for each arm, then arm movement could be solved. Another option would be to use a group of motors, and link them to your arm movements like what they can do for robotics. I know that I'm planning on doing one of these when I work on a costume I want to make. In my case, If my head was mid-chest, my legs would likely end in the knee joints, or somewhere in the upper legs. There are ups and downs to each, but I guess budget, time, and experience would sort of dictate which you use. You could switch systems later, I suppose, but it would likely depend on your method of making the arms.
If you have your head in the chest, seeing might be a problem, but you could rig up a HUD, and still be relatively comfortable I should think if you added small fans, and hid vents. The HUD is again, not necessarily something I'd do, but it is an, albeit expensive and time consuming, option.
This is of course based on another project entirely that's about 4' smaller than a Hunter, and that I've only scrap doodled for so far. :cool
Carrying a full scale Hunter to and around a convention is going to royally suck though :lol