Attaching solar light to stone post - ideas needed

Hello dear forum members,

I could use some advice on how to best attach a solar light to a stone post that holds a house number at the beginning of our driveway from the street. The reason is that the number is made of stainless steel and is practically invisible from the street in the dark when mounted on the stone. We do have one on the house as well, but the driveway is about 30 meters long.

The problem object looks like this:



The light should/must be attached like this.



Here are some pictures of the light itself.



This is the bracket, please note the mounting holes.



Basically, I want to anchor the light with plugs. However, I'm afraid the stone will chip because I only have about 1.3 cm clearance to the edge of the corner.
For now, I tried silicone, as you can see in the first photo, but that definitely didn’t hold.

I would now be interested in your assessment or ideas:
The material is like a paving stone or curb. Should I fear it will chip off? If yes, how should I do it then? Construction adhesive that can do this? The bracket also doesn’t have a flat mounting surface. Only these narrow grooves. I’m unsure whether any adhesive would hold there. I would of course also like to be able to remove it without serious residue. The silicone stains in the first picture are already annoying me.

*Drill without impact using a glass drill bit. *Screw the mounting plate to the lamp and then securely drill it further below.

The way you hold it like that, it doesn't work at all, every delivery person leaves your package there or you run around the corner, gone is the lamp.
Surface light on the block would work

The way you’re holding it, that won’t work at all, any delivery person will just leave your package there or you run around the corner, and then the lamp is gone.
Surface light on the block would work.

Nope, no one leaves anything there. We’ve definitely already received about 30 packages reliably at the front door. I don’t see why a light for the dark would change that. And going around the corner isn’t an option either, because there is a public flower bed from the kindergarten parking lot there.
Although surface light is a good search term. Maybe we’ll find something else that way.

*Drill without hammer action using a glass drill bit.
*Screw the mounting plate to the lamp and then drill it securely further down.

Do you think a glass drill bit would go through there? For the house numbers, I already had to drill for 5 minutes per hole with a 6mm/4cm bit using a rotary hammer (not a hammer drill, but a rotary hammer). That stuff is really hard.

then drill 2mm deep without impact, angle at about 20 degrees downward and drill diagonally downward with impact. Use a professional drill bit

Option 1: use diamond-tipped tile drill bits. Option 2: again use diamond-tipped tile drill bits. Shift the two holes inward and drill diagonally. Additionally, use a [U-Scheibe] for the two screws to make it a bit more stable.