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One option that worked well for me was renting a motorbike directly from local owners instead of official rental shops. It’s usually cheaper and sometimes you can get more flexible terms. You can find options like this online, for example, take a motorbike for rent in Sri Lanka here: https://getrentacar.com/en-US/motorcycle-rental/sri-lanka-colombo . Which makes it easy to arrange in advance and avoid looking around after arrival.