I'd say the problems here are:

1. The Germans literally have no clue as to where or what to attack in the US.
2. The plants that might make good targets are very scattered. From the examples given:

North American: Inglewood California
Chance Vought: Trenton New Jersey
Boeing: Seattle Washington
Consolidated: San Diego California
Ohio and Pennslyvania are the major tank plant states.
Other industries are spread throughout the Northeast US.
Shipyards are scattered along the entire length of the US coast.

3. The Germans had probably, if not certainly, the absolute WORST spy networks and agents of any major military power during the period. The British turned or shot the entire German network in their country by the time the Battle of Britain started. Up to then, what agents that did exist acted ineptly and were of absolutely no value to the Germans. There was no network in Russia or the US historically. The one attempt to land three sabatours in the US by U-boat failed within a week. The spys had little ability to blend into the local population. They had literally no clue how to travel to their targets nor the funds to do so. The FBI was on them like stink on......well you get the idea.

Prior to 1938 the US was seen by Germany as absolutely no threat in any case. The US ranked 36th as a military power. Italy had a larger and better equipped military at that point. There was literally no one in Germany who could have or would have predicted the US surge that actually occured.

Conclusion: The Germans would have put in place some inept plan. Their agents would have been caught by the FBI and imprisoned or shot in short order. The plan would fall apart. Nothing would be accomplished.