They look really cool, but I'd be worried about using thick metal bolts to hold the lights so close to where the props will be on landing. I mean I get that you need the weight to hold the pad down, but if your bird should tip, even to a small degree on a dodgy or windy landing for example, I'd worry that's a significant amount of danger added to the situation and a relatively high chance of prop contact because they stick up like that. In a battle between those bolts, props and the shins of anyone standing nearby, I suspect the bolts are very much gonna win ! :/
What about lying them flat, tips aimed at center, and velcro-ing the bolts to the rim by their heads ?