This is an issue. What I now do is create a series of routes. Each route includes the MG4 base map for the area I am travelling in. Saves space and I found you can load a decent number of maps along with your route file (Legend-C is 24 mb). This is usually good for a full day of riding (~700 kms). If on an over nighter, and I am travelling further instead of back home, I load the 2nd day's route, with the base maps for that route, and delete the previous day's route/maps. It means travelling with a laptop - but it works. This is how I've planned/routed my Atlantic Canda trip. Another issue to consider, depending on the Garmin unit, is that some models have a 'via point' limit. The e-Trex series is 50 via points per route. This is easily tweaked by going through each via point in the Mapsource file. Again....become familiar with the software and you will find a work-around for the quirks. Some of this stuff isn't in the manual.