When we went in last year, we had round-trip boat tickets. No problem obtaining the visa. The $10 is a revenue enhancement feature for entering Indonesia. Fortunately, they haven't turned into a Brazil, Chile or Bolivia.
When I went into Bali a few years ago just after implementation of the charge, no one was interested in looking at the documentation, only the $$$.
If I remember, I will bring a treat for your tenacity :-: and actual reading of the thread. :-:
If you feel better about it, bring your airline e-ticket.
See you on the 16th.