Three suitcases for one person? Sounds like she's moving to Phuket, not visiting! Jokes aside, an SUV could be a practical choice if you're traveling with lots of luggage and planning to explore the island. You'll probably appreciate the extra space, especially when moving between hotels. I'd compare available models at https://roscarphuket.com/suv-car-rental-in-phuket/ and check the actual luggage capacity before booking. Not every SUV has a huge trunk, so make sure all five bags will fit. I'd also check insurance, parking arrangements, and fuel costs. A comfortable vehicle can make those longer drives much more enjoyable.