RV Life, Sygic Truck/caravan, and trucker path all are big rig specific apps that allow full offline map capabilities. I just found out that Sygic has a plugin for Chrome and Firefox that allows you to send a route to the app so I'll probably be investing the $75 in a 3 year license for their caravan product. If I don't like that I'll try trucker path gold at $99/year. It's basically the Google maps interface tweaked for truck specific routing/POI and with full offline database. If it wasn't so expensive I'd probably just pay right now as it has the best interface of all the big rig solutions I've tried.