FWIW, I marked my wooden stir paddle with a sharpie. I hasn't worn off in 3 years of brewing and it's cheap and easy.
My other kettle has a sight glass which is much nicer.
I would always defer to Yooper but that first picture didn't look bad to me. If you've made it this long without some major growth, surely (Shirley) you're in the clear.
Any new photos to post?
What is the current gravity and the predicted FG?