The lip of the bottom of the tank directly supports the bottom of the tank, but you also have to make sure there is something under the tank to support the weight that is put down on the tanks sub support.
Not much else can go in a 60 gal with an Oscar. In a tank that size the fish will either become lunch, or if it's too large to be lunch will peeve the Oscar off due to territory issues.
MTS (Malaysian Trumpet Snails) can be put in there to keep the sand bed stirred and the Oscar will most likely leave them alone.