I'll be taking a bike to the NE in 2 weeks and just wondering if a GPS is absolutely necessary. Mainly concerned for staying on the right track between Sen Monorom and Banlung. I already own a GPS, but its 1800km away so can't bring it on my trip... not wanting to buy a second one! I'll buy another if I have too, but hoping its not really needed. Is it possible to rent one from one of the bike shops???