Hmm. If you wanted to meet 18-25 women from Europe, USA or Australia then why not move to one of those places, where they will be much more plentiful?
You are basically talking about tourist game -- there will be a few solo travellers, some of them female. There will be enormous numbers of groups, either couples or groups of 3, 4, or 5 etc. In these latter cases it will be extremely difficult to get the girl alone. I do not say impossible, it can be done but I believe you would have to set sights a bit lower in order to start developing the skills needed to achieve this feat.
I also feel that your age may work against you in this endeavour. I am 43 and have had some modest success in picking up the 18-25s but that is because I focus on women who are bored and going about their daily life, i.e. day game. This works because the woman is already isolated, thus desirous of human company, and most importantly, free from the judgement of her peers who might think I am an ageing creep.
The strategies that I use would work excellently with the local population, which is where I would be focusing my efforts. Much less well with tourists -- think about it: youeet a promising prospect and arrange a coffee with her in the coming days, so what if she has no phone? What if plans change or she cannot commit as she is attached to a group and does not know what they'll be doing a day in advance?
You might do okay if you are a night game specialist. The drunken party atmosphere is surely conducive to one night stands. You might also do okay with online, there could be bored Tinder girls left behind at the resort swiping left and right. I am not sure. But I would not really regard these endeavours as sustainable or scientific, more hit and miss really. It will also take a toll on your health and attitude to night game long term.
The key really is to build a process that works with these girls. Ideally you also want to set up a rotation for better efficiency so that more time is spent laying beautiful women and taking your fill of them, leaving time for other fulfilling career or life activities while minimising the time-consuming approach, dating and getting-to-know-you activities. This is going to be impossible with tourist game though unfortunately.
cheers, Ray