This is not my area of expertise. However, I can tell you that you have two different problems: 1. how to broadband the amplifier so it will work between 1.6-30mhz and 2. How to add band switchable output filtering.
The second question is easier for me than the first. Basically, you need to make a series of band pass filters for each band that you switch between using the amp's bandwitch.
For the first question, I don't know how to answer that. I know I had the answer somewhere, but I can't find it.