I have done 4 rotisserie pigs in the past. The first three times, a friend from the fire station had a rotisserie. The last time we rented one. A 100lb pig was kinda on the large size for the rotisserie we used. 75lb was about perfect.
We took 10 heads of garlic, cut the stemmy head off, then broke them up and got as much paper as we could easily, off. Quartered 8 jumbo red onions, and kinda broke them apart. Threw that in the cavity with a cup of rock salt, some rosemary, thyme, and sage. Then sewed the cavity closed with cooking yarn. Put it on the spit, then wrapped with chicken wire. Put the spit thru it, and put it over hot coals. Went thru about 100lbs of briquettes, plus some oak. Basted with beer(pale ale and stout...), and sprinkled with garlic powder. Every 15-20 minutes, especially as it was really cooking, we'd use pliers, and twist on the chicken wire to keep it tight around the pig. Sometimes had to rearrange coals so the thicker parts got more heat without burning the thinner parts of the pig.
A meat thermometer is nice to use.
8 or so hours later, it was awesome. Especially the ribs, and all those garlic cloves...