so if the building is 16' long, and the porch is 4', then the ridge board would be about 20' right? I'm not forgetting anything? Good teamsters have packed stuff that long down some pretty tight trails before, using mules, so it could probably be done, but it would take some rigging skill, even with machinery instead of argumentative mules. 10' would be easy. If you have the loft in there, use a nonstructural ridge. Bring it in in 2 10' parts, and assemble it on site.
Take a serious look at panelizing it. The more work that is done near civilization, the better. Less gas in the generator, less tools that have to be packed in, everything already cut, so less extra waste to be packed in. If you can drive a 4 wheeler to the cabin site, an innovative teamster could probably pack that cabin in as panels no problem. I've seen a guy drive a team of horses pulling a wagon full of dam repair materials up a trail that would give a 4 wheeler a hard time. There is a suspension bridge over the salmon river that the 3" diameter, 100 foot long main cables were brought in on a team of mules, with a loop of cable tied to the side of each mule, and those trails are not easy trails by any means.