I have been thinking this over and as you state it is American culture to tip. American hunters have created this situation in Australia. Australians generally do not give or receive tips and if I went on a paid hunt here would not tip. As it is not in your culture or ours I don't think you should either. On the occasions I guide I do not expect a tip and would take no offence if none was given. If anyone reading this goes on a hunt I am guiding please disregard the above.