Well - if it's roasting temp and continually turning, it should be safe! Just stop it every hour or two and get a deep reading with an ordinary $5 meat thermometer, still going for 195 or 200 down deep if you want it to pull apart like BBQ, just over 165-170 for safety if you'll slice it (although I'd go hotter to be sure). I didn't cook on the 4th, but I'll do my first pig of the year next weekend, an 80 pounder dressed, for about 30 family members. My little boys call ever BBQ "Burning Pig." Good luck with your spit -- please post pictures!
Big homemade smoker on a trailer, Weber grill, firepit