Two things...
First, BOTH Part 107 and Part 101 restrict UAS altitude to less than 400ft., if not specifically filming a taller structure. No grey areas.
Second, please don’t fly over areas deemed to be national critical infrastructure. No video or still is worth the bad PR the owners of these facilities feel toward our industry. My clients are primarily oil & gas and heavy industry, and believe me, they are extremely averse to exposing their operations up to ANY additional risks.
I spent a month with a major operator’s aviation department, having them look at the last years’ worth of my flight logs, my operating procedures, and my emergency contingency plans, before granting my company authorization to fly over their facilities. All because someone had flown over one of their facilities in the past, flew too close to a high voltage section of the facility, lost control of their drone, and slammed into the side of some high pressure process equipment. They had to temporarily shut down the process unit to inspect for damage and make sure it was safe to continue operating. No one was hurt and nothing was damaged (other than the drone), but now the company had a recordable safety incident, a recordable security incident, and had to launch several investigations related to the crash- and that’s not counting the expense of the shutdown, the time and effort to track down the owner of the drone, and any reimbursement the they might try to get from the pilot through their legal department.
Whenever you fly, please think of where you are flying and be respectful of the owners. If you legally flew over my house, but accidentally crashed through my window, I would want you to pay for my window. If you fly over a rail yard and crash on the tracks, stop the trains, delay the cargo schedule until someone can clean up your mess, make them have to file reports about the incident to the Railroad Commission...... you see where I’m going.
Even a safe, uneventful flight can have unintended consequences for those of us that are trying to fly after you. No matter what you do for a living, you have probably had someone before you that has screwed up that job, and made things more difficult for you to do what you do now. Please think of you fellow pilots when you are deciding where to fly. We will all appreciate it.