Related to that Borrell ask, if the men really were smugglers “like [Davos]” would they really have been hanged instead of maimed/sent to the Wall? Is it possible they were actually wreckers/pirates and therefore sentenced to death?

Well, historically speaking, smuggling was seen as associated with wrecking and piracy since smugglers do a lot of business with pirates and wreckers and there’s a good deal of migration between the various jobs. Hence why death by hanging was the normal penalty – same thing as pirates. 

But in Westeros, that’s not in tension with the Wall as a legal penalty. Westerosi law generally considers the Wall as the Plan B for most serious crimes, up to and including murder.