Topic: 385ci GPS maps

[fishbone]

I'm about to install my 385. I did a test to look at the charting. I'm disappointed that one of the rivers I needed charts for does not even show up (Lehigh River, Pa.) and a local lake is just an outline filled with light blue color.
Apparently, the $200 mapping I bought for my 998SI will not work in the 385.
What are my options to improve the GPS feature?