The only way I can apply for dual citizenship for my son is if I'm Indonesian citizen, is that right?
That is correct. The dual citizenship scheme is for children of mixed marriages. Of course, your son could always work his way up the visa ladder...kitas, kitab and then Indonesian citizenship, but it would have been a very simple matter if you were still an Indonesian citizen.
Then again, you might consider reverting back to your Indonesian citizenship, but I have no idea what is involved with that move. As you know, while the US allows for dual citizenship, Indonesia does not...except for the temporary dual citizenship of minor children born to mixed marriages. This is all very complicated stuff, and you will need to really get in to it very deeply.
Since you are all American, this will complicate matters in so far as you setting up a CV company here in Bali. For either a CV or PT company you will need an Indonesian partner. There are 100% foreign owned companies in Bali, but they are very expensive to set up, and sooner or later a minimum 5% Indonesian partner/ownership will be required...which I believe has to happen within the first 5 years of the company start up.
I would suggest you begin discussing your business plans with some professionals here in Bali, for example, PT Bali Ide, or search the archives here for lawyers in Bali, as many of them specialize in foreign business start ups. Cheers!