Your idea of an observatory on Bali is most commendable and rather ambitious. Of course, an astronomical observatory in Bali is far from ideal, but since your purpose is not to do research, but simply to open few Balinese (and expat) eyes to the wonders of the heavens, it would be most appropriate any place on the island (and, as you mention, what a good excuse for a beach party on a remote beach!).
I understand that Denpasar officials are presently reviewing a proposal from Newman Bio Marine Pte Ltd., to build a 10,000 m2 public aquarium project in Sanur. So, why not a small observatory? It would make a unique attraction, on a par with the Bird and Reptile Parks, and the Aquarium. Since a large percentage of the tourists come from the northern hemisphere, what a great opportunity to discover a new part of the celestial sphere. That would make for a great attraction. Of course, now we are talking $$$.
I cannot give you any advice on optical telescopes, as you seem to have a wide experience in the field. I have never used a telescope in my work, much less built one. I only used satellite platforms for x-ray astronomy (My experiment, HXX, on ANS (the Astronomische Nederlandse Satelliet), launched August 30, 1974, discovered a new astrophysical phenomenon: the x-ray busters). However, when everything is said and done, I believe you would be ahead of the game buying a commercially available telescope, either an 8” reflector, or Schmidt-Cassegrain. Since I believe your main interest is to look at the moon and the planets and their satellites, I would favor a Schmidt-Cassegrain. For deep space, a Dobsonian reflector would be ideal. You can get either type, new ones, in the US for under $1,000 + shipping. I would think you could do better in Australia (but I have no idea about prices there, compared to the US). Maybe Davo could be of help there? I am sure you have already checked eBay: they have fabulous prices there also. Again shipping may be costly, and what about the Indonesian customs?
Good luck. Whatever it turns out to be, it’s sounds like a great worthwhile project.