I am trying to find a fall back solution when the UPS module comes back with no results, due to overweight orders.

Currently I have the UPS module producing shipping rates for orders. However, once the order gets to big UPS is unable to ship it and does not return rates. In this case I would like a flat rate shipping option to show up, allowing the user to continue checkout. However, I don't want the flat rate option to show with the UPS options. So you get one or the other UPS or Flat rate, never both.

Been banging my head against the wall all day long... Any suggestions would be greatly appreciated.