If You are still looking for a way to implement adsense code You can add it everywhere inside the functions:
For example here in Your advanced theme in the function
// ADSENSE BEGIN
$this->output('Your complete adsense code');
// ADSENSE END
This example shows the adsense after the content of a single question.
You can use the class
to move the code or set borders or something...
It should work in qa-theme-base.php as well, but it is allways better to build an advanced theme and add changes to qa-theme.php
Read more at