You wouldn't be distributing the weight correctly, as you wouldn't have the corners of the tank lined up with the legs of the stand, or even close. Depending on the design of the stand, you could place board of the correct size on top that would distribute the weight, but I'd still be a little wary about a 7" shortfall. How long is the tank itself? If you give some info on the design and construction of the stand, it might help asses it's use.
55g FW South American community tank
20g SW FOWLR tank
2.6g Fluval Spec III SW reef