Force Express Mail International on high dollar amount orders

I am using the United States Postal Service API rates (web tools) with our shipping rates are based on weight.

On international orders I offer 1st Class International, Priority and Express mail international shipping options.

Is there a way to Force Express Mail International on high dollar amount orders? I want all international orders over $500 to go express mail international only, while still offering all the international mail classes if the order is under $500, also without effecting domestic USA shipping.

Is this possible?:unsure:

old bumpy....:sadwalk:

I added the optional shipping insurance mod to help offset the risk, but it might be nice in future to have a feature where high dollar amount orders ship only express (tracking) and still offer cheap shipping (no tracking) to customers on smaller orders.