Art,
I've done Porchetta before...with a much bigger pig....we boned it, stuffed it, trussed it up and cooked over charcoal on a rotisserie. It was phenomenal, but without the head it's a big hunk of fantastic pork.
I may in the end have to remove the head....butterflying it, and hooking it at the shoulders....I think the head may be to far above the rebar, it may interfere with the lid closing. I am going to talk to my Butcher this weekend, if she can't assure me her pig will be under 25lbs, I found a place online that guarantees their Suckling Pigs are 24lbs and under.
In doing some research on little pigs, I'm finding that if they are under 40lbs, their bones are still mostly collagen, which makes them very difficult to overcook. It also makes them very sticky and of course sweet.
I have extra time off around the Memorial Day weekend, so that is when I am planning on giving this a try.