or the "k" in hooker..........maybe they will 'apt' to pronounce it as 'g', but like you said its the lesser of two evils. A good language learner will realize that it is neither g nor k in the strict sense (it could be k, g, or even c in english, as you point out) and learn how to pronounce it correctly. But I think that no typical western tourist in Thailand takes that much time, so for me goh chaang would be better than โค koh ช้าง which makes me think of โคถึก haha