Generally a multiday trip covering at least a few hundred kilometres. The general problem will be cache detail management, you simply have thousands of caches loaded into GSAK and not all are going to fit into the GPS.
Firstly , and it helps a lot if you are a premium member, download all the caches anywhere near you might be going. This can be done with multiple queries, retrieving 500 caches at a time. To do this pick places along your route, every 300 kilometres or so, and look up the coordinates. Use these coordinates for your Pocket queries. Once you have the results from this import the cache details into GSAK.
At his stage we now have huge problem, way too many caches!
To get around this we want to use a filter based on the route we will be taking. Using Mapsource create a route by manually adding each straight-ish section of road from Start to End. Save this file as type gdb. (Note, the autoroute will not make the intermediate waypoints you need for roads that are not straight so don't use it.)
Now open up GSAK and create a new filter as follows:
- Go to Set filter and create a new Arc/Poly type.
- Import the gdb file you have previously made. You will see a list of waypoint coordinates appear.
- Set the distance to about 20km. (This is roughly how far you are willing to go out of way for a cache, 5km may be better.)
- Save the filter with a unique name.
- Click on the go button.
You will now see the number of displayed caches drop.
Now back in GSAK we need the data in two places, namely the GPS and typically a PDA. The data can be directly uploaded into the GPS at this stage so do it.(<-important step) For the second version export the data in GPX format. This GPX file can now be opened in Mapsource of even Google Earth to view the caches along the route. If you are not using Mapsource with a laptop in the car then print out the maps to make it easy to see which roads to travel.
Given you GPS can only store a limited number of waypoints a PDA with suitable interface cables can be usefull to store and load local waypoints on the road. This is very useful when undertakeing unplaned caching in areas with high cache density over a long trip with numerious potential routes. Plugins are available for Waypoint_management_software like cachemate specialy for this purpose.
Caching listing on your mobile phone
If your mobile phone service has internet access and you don't mind footing the bill try http://mobile.geocaching.com.au. Information on this site is designed to be as "low band width" as practicable. Entering the towns post code in the search box may be a good starting point.