Supports for Light fixture mounting legs

[balistidae]

Well I just got my 250w mh running and was temporarily supporting it on the glass top. Within 5 minutes the glass top shattered and the light almost fell in. Needless to say I am now going open top.
The issue is now I need something for the legs to stand on. It is a 54g corner bowfront and the light is only 24". So the braces will need to run front to back on the inner trim lip. Does anyone have any ideas of what to use?? Thank you