We've done two pigs on a portable rotisserie setup I got from R-Grills out of Germany (or maybe Austria - I think the owner is Austria and the equipment is made in Germany). I've posted pictures here before. The first was a practice pig to learn with before doing the 2nd for a large family gathering.
Around here, pigs (70 - 100 or so lbs) are $2.89 lb and suckling pigs (under 40 lbs) are $4.99, so I can get a bigger pig for the same cost as a smaller pig, so my pigs have been bigger.
I've also found that it's very difficult to get a pig that hasn't been butterflied, which isn't ideal for spit roasting. I wasn't prepared for that with the first pig and had real difficulty securing it to the spit. I was prepared for this on the 2nd pig and had the stuff to stitch the pig up.
Also, the rotisserie kit came with a long steel fire pit but the pigs were longer than the fire pit; the hands and shoulders didn't get fully cooked. I remedied that by getting another fire pit.
For both of these cooks, we seasoned the inside of the pig with my standard SPG rub. I planned on seasoning the night before the cook but the practice pig was still frozen when we picked it up; it spent the night wrapped in plastic in a water bath in the tub to the out so it was seasoned just before putting it on the spit. I did a better job of communicating with my supplier on the 2nd pig so it was thawed and seasoned the night before the cook and spent the night in a big cooler with ice.
After getting the pigs on the spit and positioned on the rotisserie stands, we coated the outside with soy sauce to season and we some color. The 2nd pig cook was a big success.
Based on these experiences, my advice is:
o Assuming the pricing is similar in your area, consider doing a bigger pig so you have more meat for the same price - leftovers are a good thing and folks tend to feel less sorry for the bigger pig than the do for a "piglet."
o Get a non-butterflied pig if you can; be prepared to do some sewing regardless. I got a big needle with a knob handle for this from SpitJack.
o Verify with your supplier when you're going to pick up the pig in case they get a frozen pig so that the can thaw it in their big refrigerators before you pick it up. My supplier says the don't know ahead of time whether their supplies will provide a fresh or frozen pig.
o Do a practice pig ahead of time! The lessons learned from our practice pig made the "real" of cook much easier, less stressful, and a big success.
We had planned on doing another practice pig next week, only this time stuffing the pig with apples, onions, and maybe some cabbage, but my mother fell and fractured her femur Wednesday so I had to cancel. Bread situation but it was semi-good timing since i was planning on ordering the pig after lunch that day.