How should I scale intermodulation products?
What you can do -----reduce the power levels by 6dB or 10dB or 20dB.

If the spur drops exactly double the amount of power reduction --- the spur is 2nd order.

If the spur drops exactly triple the amount of power reduction --- the spur is 3rd order.

The spurs generated by overlapping 2nd + 3rd (or higher) are the challenge.