Hello Roland,
I managed to find 2 small routes and did some tests with it
First route had 44 tiles (total size of png files = 45 Mb ).
Second route had 56 tiles ( total size of png files = 57,8 Mb ).
I could create a new map with Dem elevation and ground textures, of both routes.
Now, I have some idea what to expect. 71 Tiles ( total size of png files = 80 Mb ) is to much. For small routes I can use orthophoto with provider MS Virtual earth.
I also used the sysinternal VMMap ( memory check ). Looking at this check is already a big study.
Here is the result
Best regards
Kurt