This is a difficult design problem. For such a wide frequency range there are usually two amplifiers for sub ranges and combiners. But with your high power requirements the combiner losses would require 1 kW or so for each amplifier and a lot of heat removal fins.
If this is part of a larger system you could use switches to route the signal and load to the appropriate amplifier. That is if the frequency of your signal does not hop rapidly over the whole bandwidth.