I have a 54 gallon corner also, and it was def a PITA to light! I started out with a 30" PC light resting on the glass versa top like you were thinking of doing. It worked okay, since all I had were zoas, shrooms, and fish.
I have since upgraded to a 24" 6 bulb T-5 fixture, and I had to hang it from the ceiling. Good luck. Corner tanks are tricky, I should have realized that when I was trying to fit a sump under that tiny little stand!
Good luck!