Have you looked much into international organizations such as Mercy Ships or Operation Smile? I know a couple of folks who spent a lot of time with Mercy Ships, which is a Protestant organization that has missions all over the world and may be something to look into. Operation Smile is emphatically medical in its focus – cleft palate repairs and other craniofacial repairs, basically – but I guess the idea I’m posing is that a well-established international organization might be a good place to look for your next international volunteering; they definitely would have the organizational structure and set up for efficiency that you might find useful…