You don't HAVE to work remotely to be eligible for the DTV. There is something called 'soft power path' which allows you to apply if you enroll to Muay Thai training or Thai cooking classes. If you're interested in that you can contact Zee @ KLMT (Khao Lak Muay Thai)
If you plan on partaking courses yourself why not apply for a DTV for yourself instead of piggybacking? You'll save him the back pain as well as I'd imagine it won't be fun to piggy back someone for 5 years...