The china box thing is fine, but basically produces steam roasted pork along the lines of kalua pig, which is fine, but if you're looking for southern whole hog barbecue, however, you need to look elsewhere. Here, for example.
Get your hog split so it will lie flat (you need to have the ribs sawn for this) and lay him out on a sheet of (clean) polyethelyne so you can see how big he is. Build a wood frame (2x4's should be fine for one this size) about a foot larger on all sides than your hog and staple heavy-duty hog wire or other non-galvanized wire fencing on it so it looks sort of like a bed frame.
Then securely wire your hog down on the frame with the skin side up.
Dig a pit 18" in deep or deeper. Build a hardwood fire and let it blaze away until reduced to coals. When you can hold your hand over it for 10 sec without flinching, put the hog on, skin side up. Lay a clean canvas or heavy poly sheet near to the pit to give yourself a place to put the hog while you're maintaining the coals. Keep the fire warmer at the ends than the middle, since that's where the hams & shoulders are.
Every hour or so, flip the hog on to the canvas and mop with the mopping solution of your choice, but be careful its not too sugary (like apple juice) or it will burn. Plain salt brine with some lemon juice works well. Keep the pit fueled with hardwood lump charcoal, or burn hardwood in a separate fire pit and shovel the coals in.
Keep doing this until done. Should take 10 - 12 hours depending on ambient temp. Remove and separate the hams, shoulders, loin and ribs. Note: the skin will not be crispy -- if you want crisp skin, you need to use 2 bed frames and cook on both sides.
Add more fuel to the pit and put the ribs on fat side down to crisp them up a bit.
Note: This process is best done overnight with the aim of dining at midday the following day. Doesn't work well in cold or windy conditions. Continuous consumption of alcohol and telling of lies during the cooking process is mandatory.