We bought half a hog this year, too, and looked into how to make bacon and ham at home without nitrites. The ham thing seems to be a balance between the time it takes to brine, the time it takes to smoke, and the moisture level. It's hard to find straight answers about the "danger zones" in terms of preventing the growth of botulism and other nasties, but as far as we could determine, if you don't use nitrites in the brine for ham, you want to keep it less than 4 or 5 days in the brine (below 40 degrees, refrigerated) and you don't want it sitting in the smoker for more than 4 hours with the meat temp under 140 F. (Country hams are different because they're not wet brined, they're heavily salted on the outside which dessicates and kills any bacteria present on the surface of the meat, so it doesn't have a chance to grow or get inside, and then they're dry aged kind of like prosciutto, but that's not a project we were ready to tackle.) Don't quote me on any of this, because it's just what we were able to figure based on all the dire warnings balanced against what we could fine on traditional methods. (BTW, nitrite in the form of salt peter was used for meat preservation for hundreds of years, probably still is in some areas.) We noticed that the nitrite-free hams available to buy are small cuts, 3 or 4 lbs. max, not whole hams, which clued us in to the shorter brining and smoking time possibility, and we think they also probably either brine it by injection or by vacuum, which would really shorten the time required. I believe botulism likes to grow in a wet environment between 40-140 F., so you want to minimize the time the meat spends in that zone.
We ended up using nitrite (pink salt) for the ham, because we just couldn't get a good enough handle soon enough on the situation to feel comfortable doing it without it, and we wanted to get it done. Next time, we'll cut the ham into smaller pieces so it will successfully brine and smoke in a shorter time. Bacon without nitrites is no problem, because the cuts are so much smaller so it cures and smokes very quickly. And let me tell you, home-made ham and bacon are so, so, so much better than any I've ever had elsewhere. I do wish there was a clear guide to making ham at home without nitrites, no one seems to want to take responsibility for saying just exactly what could land you in the hospital and what couldn't.