After appearing from the train wreck, Wilhelm will spend some time digistructing a surveyor giving Vault Hunters crucial few seconds to reduce his health. he will construct more surveyors as time passes on which can recharge his shield at a much faster rate.
One way to get this achievement is to apply slag the moment he appears followed by shots from a high power corrosive gun aimed at his midsection, so as not to accidentally destroy the surveyor. Because he lacks a shield of his own and can only digistruct a single surveyor at any given time, slag followed by more corrosive shots will counter the shield provided by the surveyor bot and hasten his demise.
Level differences are also effective, and Vault Hunters can return to Normal Mode to kill him after gaining weapons and experience from True Vault Hunter Mode. Again, corrosive damage from accurate weapons is sufficient to quickly overpower him.