Dave is right. You simply do not have enough time for this itinerary. VN alone takes 3 weeks to travel from HCMC to HaNoi or the reverse. Thailand is huge and you will need 3-4 weeks just trying to visit the main cities and the beaches. Even if you only allow 1 week for Cambodia and 1 week for Laos, you will have no time left for Malaysia, Singapore and Borneo. You need to decide what countries you want to focus on. If Borneo, Malaysia & Thailand are your top priorities, then drop VN, Laos & Cambodia. If Thailand, Laos, VN & Cam. are your top choices, drop Malaysia, Singapore & Borneo. I would make this decision before going much farther with your trip planning. Good Luck.