While I have the option in basecamp to select which map features are displayed, there is no option to customize how this features are displayed. For example I would like to be able to select a special color for topographic contour lines, so that this lines are visible over birds eye view images. In a garmin oregon this lines are drawn in a dark red color which gives enough contrast to distinguish the lines over birds eye imagery. However in basecamp the lines are drawn in a brown color which makes the lines almost impossible to distinguish over birds eye view images with forest coverage.
Would changing the color of the particular line you mentioned sufficient to solve the issue you are having? or are there a lot of other lines you wish you could customize?
There is a way to customize every element of Garmin's vector-based (.img) maps using a feature named "custom types". This is something which is normally only used by mapmakers, but if you are comfortable with computers, it may be possible with Garmin's own maps. See the section starting on page 33 this article for some background: http://www.cgpsmapper.com/download/GM8DocV2.pdf
yeah, I think custom types may be a way to set the display color, but It may involve more tinkering than I am willing to do for my current needs. I hope this might be addressed as a new feature or option in Basecamp at some point.
The newest Nuvi models, such as the 3700 series, have a feature called Map Themes that let you choose different styles of map display from a menu. Perhaps this could also be implemented in a future version of BaseCamp? It is controlled by XML files on the unit.