See this an[swer [answer about how to cache imagery][1]
As there is a limit of 2GB in the folder that holds the cache you will need to get creative. Basically you could divide your 6.900 plots into say, 10 files, and use the caching method 10 times.
Each time you do it, and before you run the tour you need to rename the folder where the current cache is being stored so that Google Earth starts from scratch. At Then, when you use Google Earth you need to make sure that the end you combine all of right folder has been renamed to the files into one final standard Google Earth cache folder...
folder:
Takes some time but should work, I must admit I have not tried a complete round myself. *C:\Users\faoadmin\AppData\LocalLow\Google\GoogleEarth\unified_cache_leveldb_leveldb2*
Of course you will not be able to use the very valuable Google Earth historic imagery,
[1]: http://www.openforis.org/support/questions/126/how-to-cache-google-earth-imagery/900