I think there is something to the argument that the South could have won using Hanoi's tactics, given how much weaker the army was at the outset of the Civil War compared to the Vietnam War.
The United States Military at the beginning of the Civil War was small and somewhat amateurish compared to the military machines that some European countries had at the time. The best known tactics and strategies were European; cadets had to learn French at West Point in order to read the books, and George McClellan had spent time as an observer during the Crimean War in order to learn. Some of the men who would be most instrumental in winning the war (i.e. Grant, Sherman) were not even in the army. The army was filled with political generals, and there was a fair amount of bumbling, trial and error as less competent generals got weeded out. Tactics had not caught up to the innovations in firearms (the Minie ball), nor had medicine. The home front was painfully divided, with strong and influential influences against flighting the war, particularly in the border states. If a guerilla war had been waged against this army before it evolved into the larger, more organized force that it became by the end, I believe that the morale of the Northern public would have eroded pretty quickly, and the domestic pressure to get out would have been much greater than it already was, perhaps tipping it for good.
Contrast that to the United States Army at the outset of the Vietnam War. It was arguably the strongest, most sophisticated on the planet, with many of the officers instrumental in the World War II victories still active (or President.) American military manuals were standard in military academies around the world. While Eisenhower had the wisdom not to get involved when presented with the optioon in 1954, understanding well the risks, Kennedy and Johnson were more easily swayed, since their military experience was superficial. The Armed Forces were confident and had the technology, and probably could have won any war that it fought wholeheartedly. What they lacked was a good reason to be there. Worry about public opinion made Kennedy very cautious and Johnson susceptible to overconfident advice. It was domestic public opinion, learning of the horrors of the war, that was the main reason the country got out of the war.
Imagine the same domestic pressure during a time when the United States was much more divided and the people being attacked were fellow countrymen and women.