DK, you remind me a bit of my dad. His mantra was why buy it if you can build it? Sometimes that drove my mother batty when his inventions didn’t work, but he did outfit his own car with an alarm system long before they came on the market. He also rigged his bicycle handlebars so he could hide a knife inside, in case he needed to defend himself while biking around the Detroit riverfront. His basement workshop was an adventurous and fun place.
Even if presented with a kayak rack made of Purpleheart with brushed stainless steel hardware, I would not drill holes in my car roof to install it. Aside from possibly affecting the roof strength, drilling holes in the roof is certainly an invitation for corrosion. Not going to do it. But that doesn’t mean I would scoff at anyone who went that route.
Ingenuity is wonderful, but we all dance to different music.