I'm exploring a new-to-me area where the bottom has virtually zero relief and all structure is "swiss cheese bottom" that can only be identified by hardness or presence of fish. I have been trolling and recording sonar logs that I've been importing in Sonar Viewer, finding promising spots and then manually entering into my GPS unit.

What I'd like to be able to do is import all of my GPS waypoints and sonar logs into a single map view that has a hardness layer to help me locate new areas to explore more carefully.

Is this something I can do with Reef Master? If so, how? Thank you!

You can import waypoints and show these over any map that you generate, including hardness areas. You can also create new waypoints over the map or within the sonar viewer window on marks of interest. Any waypoint created within ReefMaster can be displayed on any window, including map views, so you should be able to achieve what you want to do. Waypoints themselves aren't included as part of map exports (apart from, optionally, image exports) so you would need to export these separately and have your unit show them over the map.