I had assumed the article was a bit old, and you are right, they seem overkill, and I am sure they would hold up, but they CAN get hot.
And you are correct, but there is a way to adjust the intensity of LEDs, it's actually very very easy
It is very technical, if anyone is interested in how it works, let me know, and I will explain, but it really is boring technical stuff
I have look around a bit, and depending on the color of the LEDs, a side marker light ready to wire up with a 3 wire lead (ground, parking, blinker) Would run anywhere from about $100 for blue or white to about $50-60 for yellow/oranage/green/red. These are BALLPARK figures (could be more or less), not sellling prices, I am waiting for responses to see fi there is a market for these, or I may just make them on a individual order basis. (individual basis would cost more, so I am hoping there is some demand for these.)
I am not sure, I have looked around the internet, and found some LED lights you can buy, but they cannot be on and blink too. The one I make would be able to do both.