Cache or load saved map

Sure. I can explain how I am doing this.
First I use Mission Planner on PC to grab the maps I am interested: TAB Flight Plan / Map Tool (right click) / Prefetch.
Once you select area and zoom, maps will be downloaded on your computer on this location (Mission Planner\gmapcache). Before extracting the new maps, I do clean (backup) the existing old maps, because I don’t want to put on Droidplanner all old maps. Once new maps are extracted on PC, I copy that folder content (under gmapcache) and then transfer to my tablet (Nexus 7 connected to my PC by USB).
On Droidplaner you need to activate using offline maps (Settings\Advanced\Use offline maps - checkbox)
The folder containing maps from PC is copied on: Nexus 7\Internal storage\DroidPlanner\Maps
Then disconnect tablet from computer, disable WIFI and open Droidplanner on the location where maps should be. You should see maps offline. (I said to disable WIFI to be sure maps displayed are offline maps). Then enable again WIFI.