My cousin and his wife have one down at philip island, I think they have had if for around 2 years now. They have been heavily into property investing for many years so were fortunate enough to be in the position of buying their holiday house and only having a very small mortgage on it. So they don't need to rent it out, lucky them! They allow family/friends to stay there when they aren't using it and stuck to the fridge they have a laminated set of 'rules' lol! Most of it is pretty common sense but I think its good to have it in writing for all to see IYKWIM? Things like 'if you break it you replace it' and 'please leave a donation for electricity bill lol' and 'please vacuuum/mop before you leave' etc. So far I don't think they have had any issues.

Best of luck! I have no doubt that the two of you will be able to make it a reality one day