Return ticket requirement for Visa

This is no problem and it's very doubtful that you will even be asked to show your return ticket at VOA processing.  However if you are asked to show the return ticket, you can simply explain that plan to renew your VOA for another 30 days while in Indonesia.

Have a great trip.

You need to be careful as a lot of carriers into Indonesia ask for a return ticket before you check in. I was challenged in England despite having the correct visa stamps and I know people who had to buy a return ticket in Singapore before being allowed to fly.
But most of the time no one asks or checks but just so you know that it does and can happen.

"I know people who had to buy a return ticket in Singapore before being allowed to fly."

I wonder how they were dressed!   

He was a mess, he normally is....