Hangi/Pit oven question

[mick senior]

I've got a chance of doing a hangi on a scout camp and I'm in need of alittle advice.
So my idea was pork joint, enough for around 20 folks but what I need to know is how big a pit and how long to cook?
Now, according to various books I have they suggest the pit should be 5x the size of the meat. The meat in the middle and surrounded by veg. Would you recommend the meat/veg being wrapped in foil? (would use leaves but there isn't any good ones nearby).
As for cooking time, one book states that a hangi will cook most things in about 1.5 hours, doesn't seem long enough to me for such a large joint of meat. Maybe better to follow cooking times on the label.
I'm not a total novice at this,I've done a few one man pits before so I've got the general idea. Just wanted advice on doing something abit bigger.

Mick.

 

[Greg]

This hangi took about 4hrs to cook the suckling pig. I hope this gives you a general idea.
As for the veg, if you can get yourself some muslin bags they will do nicely.

I haven't got a photo of it sealed with mud!

The meat literally fell off the bones!