AAAWWWW your making me nervous ! !
I can just see a wet floor, broken glass and little fishes flaping around.
Sorry MDF may last but I prefer "a brick SH__THOUSE" to place my tank on.
I have my 36Gal tank on a solid timber unit and this I reinforced with bracing uprights and used additional screws to ensure nothing comes apart.
You must also make sure the area the tank is placed on remains level even with a sheet of foam underneath - MDF has a well know problem of bowing / warping.