You are bringing double the amount of most people so you're off to a good start! Plus have someone to share costs with which helps. My travel buddy got our van from a Australian company that were selling it, he didn't trust other backpackers haha. That's not to say that there wont be some good ones from backpackers. Yeah helpx (volunteering) is a good idea. theres some amazing places on it, I really regret not trying it out