My parents have asked for something similar.
I had a larger single 12 volt landscape light..
Drilled a hole in the top of the light.
Using silicon, I attached a solar landscape light to the top of it.
Sprayed silver paint inside the top.
Then put a small reflector in the bottom.
I then took a 5' long piece of 1" conduit, put it in a large tin coffee can and added quickcrete (and water).
The landscape light slides down into the 1" conduit perfectly.
Note: The solar light is the same type as used in my Solar Safety Cones. A neighbor gave me several and I put new batteries in them. Lowes has these solar lights for sale at $2 each. The new rechargeable batteries were also purchased in the solar light section at Lowes.