If you're going to do something that foolish, at least wait until the trades calm down in the late spring. Even then, it's a long way to weather.
Take lots of fuel and don't forget something to defend yourself from the nice "fishermen" you may encounter off the VN coast.
BTW, why would you want to go to VN? I know a guy, native Spanish-speaker, who lives winters in St. Croix and for years kept his boat in PLC during the hurricane season. His sister lives permanently in PLC -- she used to look after the boat for him. He says he won't go near the place -- it's just not safe. Bad enough that foreign yachties are getting shot, but apparently even the locals are concerned for their safety in the current environment.