Forget legs, they are nothing but a violent nightmare as your scaping activities can attest to. Hang the lamp on some simple chain. The light on my 2nd tank is suspended from common ceiling hooks. The light on my 1st tank is suspended from simple eye hooks in the bottom of a shelf.
The chain on both can suspend the light fixture less than one inch from the water surface. In less than 3 seconds I can have either light fixture suspended 36"+ from the water surface. Maintenance activities are SO much easier.
Maybe it's just me, but when it comes to tank placement the first thing I look for is light suspension. This hobby is supposed to help lower my stress, not cause it.