Getty Mexico's Riviera Maya has been changed throughout the years from a sleepy backwater into a world-class getaway destination. And together with the tourism development, mobile experts and digital nomads have flooded to towns like Playa del Carmen and Tulum. "Tulum has actually cornered the market for being eco-chic," says McMahon.

It's as trendy a destination as St. Barts, St. Tropez and the Greek island of Mykonos." Until now, a 1,000-square-foot oceanfront apartment in Playa del…