Diabetes Supplies Abroad

My son is T1 and 8yrs old. Our family is preparing to become full time cruisers on a monohull (yet to be purchased). We are planning to be away for two years exploring the world and home-schooling. Currently he is using a Medtronic Paradigm Revel pump and the Mio infusion sets. I'm trying to figure out the best way to ensure we will be able to get insulin and pump supplies. Does it work to have family back home mail it over or will it get stuck in customs or stolen? We are hoping to keep our current insurance coverage through COBRA, but I’m not sure how to keep the prescriptions filled and how to get them when we are overseas. Does anyone have experience with this challenge? Is it difficult and/or expensive to get Diabetes supplies outside the USA?