Hi Tom
I don't know about getting a license in Lombok but I have got mine a few times in Bali so if you do decide to go for that option I can give you the address and details.
On my last renewal they had cleaned up thier act, and only the person getting the license is allowed in the office, no "agents" and there was nobody being taken off into a little office to arrange it privately. They have a time flow chart up and my renewal took exactly as long as they said - 45 minutes. A new license was 1.15 I think. I have all the details elsewhere on a post I made on BEF if you need more info.
If you would rather do it in Lombok it might be worth having a word with Made as he is friends with most of the police in Praya. He would certainly be able to find out if you can get it issued there.