Garmin 67i no custom map menu option, pulling my hair out.

At least on the 66i, what I think you want is on the map configuration screen. From the Map screen > Menu > select Map Setup > Enter > on the resulting screen select Configure Maps > Enter > from the resulting screen select Custom Maps > Enter. This will result in a list of all custom maps present on the device. Each has an on/off toggle. To change visibility, select a map, press Enter and follow the screens to enable/disable from the preview.

On the 67 the menus are different. To use custom maps go to Map Manger in the Main Menu, and select Custom Maps. This option only shows if custom maps are detected. A list is shown where you can enable or disable individual maps.

You also might need to disable map layers to have the custom maps show. This can be done by pressing Menu when on the Map page and selecting Map Layers.

That's what's weird, is that no other layers are enabled, I've disable them all. Unless it's possibly an issue with the KMZ file not being recognized or something. I've done the conversion from PDF now twice, and same result both times.  

But I'm starting to think I have a defective unit, as I can't even get the included TopoActive maps to show, not even the option to enable it the layers menu. So I deleted it, and I'm in the process of redownloading the TopoActive North America and now I can't even get it to finish downloading without bricking the unit and have to restart it and start from scratch. From day 1, the only thing I can see is the Base map layer with major highways and nothing else. It's been a very frustrating experience so far

Is the custom map listed under Map Manager > Custom Maps?

And do you have the maps (both custom and TopoActive) on the internal storage or on an SD card?

Also when reinstalling TopoActive maps, this is best done with a computer and Garmin Express. Downloading the maps on the device itself is very slow and unreliable, especially with large map regions like North America or Europe.