[X]The Grass Earth Route: Grass has always been an opportunistic bunch, but they have always been lax on border security, as well as several dozen other stupid shit if the stories you heard from Ayako were true. But in the last war, they were opportunistic against Earth Nin, and they have a heavily guarded border, with a lot of trade and merchant traffic. Maybe you could sneak in.
[X]Charter a Ship: It's expensive, and will get into your mission funds… but it also carries the least risks when it comes to running into hostile ninjas. It's a nice two-week vacation on the sea, where you can get a lot of training done. If it isn't a merchant ship. And the only ship to charter is a merchant ship… Shit.