66i and BaseCamp

I like to plan trips using BaseCamp. The big screen is nice but more importantly, it works without an internet or cell phone connection. Much, if not most, of my campsites have no service of any kind. I did a download of free public topo maps for Australia (gmapprom1.img on the SD card plugged into the 66i). These show correctly on BaseCamp (with the 66i plugged into the laptop) and make it easy to plan and research using the big screen in the Australian back country. The 66i has a copy of TopaActive North America. I would like use it for trip planning / research in BaseCamp but can not find a way to get it to show up. Is that possible? Why can I see the Australian map and not TopaActive?

I've tried the online tools. They are fine but completely useless without a connection. I know BaseCamp is old and has always been clumsy but it still seems the best option for offline work. 

Any suggestions for a better way to go?

Thanx

Ron