Excellent Idea Aaron, just fly slow in that Loop. I would first do some practise with a HoolaHoop at your Backyard. Just keep in mind that that Monument is made out of METAL, and METAL Objects can have a Bad Effect on your Compass, just pay extra attention as the Drone may move left or right due to Compass Interference.
That Metal Monument is not a very big structure like a Bridge, but if you get Errors or the Drone exits P-GPS and enters ATTI, just land the Drone as soon as possible, so be Prepared.
Also when you fly outside keep it in VLOS so that if something happens you land immediately and can go recover your drone, if you keep your son with you all the time and act as Spotter it is better, so you have some Help.