Thanks! David put a lot of effort into making the config really intuitive so he'll be pleased to hear that.
The UAC is once for the installer and once for the app since it requires admin privileges to apply the block.
I don't know spefically about your internals, but you could try to install with user rights only (= no UAC) and then only do UAC when you need the block?
If I remember right the reason the installer needs admin rights it to be able to kill and overwrite a previous installation of Temper