A great alternative for foreign tourists is converting bitcoin and cryptos to fiat. That is one that will keep them out of legal trouble because Indonesia does not legalize bitcoin as a legal tender.
Using fiat currency when you are traveling to a new country is always the most convenient method. I don't know about regulations on Bitcoin in Indonesia but if their government does not prohibit Bitcoin and its transaction as payment method, locals and travelers can use it without legal issues. They don't need Indonesia accept Bitcoin as legal tender to use it for transaction and as a payment method.
Big problems for travelers and locals only exist if the Indonesian government says Bitcoin transaction is illegal and prohibited there.
Cryptocurrency in Indonesia. That article says you can use cryptocurrencies as commodities in Indonesia.