Interesting stuff,

So what exactly was the plan by the Wijeong Cheoksa types to counter Japanese and Western gunboat diplomacy and expel the 'barbarians' (so to speak), given Korea's relative lack of military power or international standing?

In the case of Japan, even the most hardcore 'Revere the emperor, expel the barbarian' adherents (i.e. Choshu and Satsuma) came around to buying modern rifles and artillery and training in Western tactics once they saw their military weakness. Heck, when a British warship penetrated the defenses of Nagasaki back in 1807, there were some far-sighted officials who began buying western guns and learning about western military tactics to counteract the threat.

There seems to have been a comparative lack of urgency or perhaps a deep seated delusion at what Korea could accomplish. If I recall, the Daewongun's response to the challenges posed by the French and American attacks was to attempt to build a battleship made up of feathers (!) (among more practical projects like building a steam ship or bulletproof cotton armor) and to arm peddlers and tiger hunters as troops (I read that there was some historical ties between the ruling dynasty and the peddlers which made them particularly loyal)