I just read your blog post Mikko. Shame no GTs as those conditions in your pictures look excellent - the current is really running.
The charter you used is Ena Fishing with the guide Pak Kebut. I don't think there is any problem saying that here. He's a good guide, albeit he knows more about jigging than he does topwater GT fishing.
Now that Xplore has lost their captain and all-round maestro, most folks would choose to use Adhek for GT fishing.
The tube flies you mention in your blog are used a lot here for trolling for various small tuna species. Mahi-mahi will take them as well. Traditionally these were made from goat hair, but nowadays synthetics have taken over. You can though still find the old boys tying the superior goat hair versions on the dock at Serangan.