You cant predict the size of your pagelist while creating your section ,So it is probably not a good idea to try to code like that.
Rather you can try the below approach !
1. Create a placeholder property and use it in the section where you want to display your penultimate pagelist property
2. At runtime, once your users filled up the data on the pagelist or your pagelist is completely populated and available on clipboard, you can use an activity or data transform to reach to the last node of the pagelist
3. And then set the value of the place holder property to the last one of the page list.
I think that you could use the .pxListSubscript property to do this. This is a string property that holds the index of the pagelist. E.g to calculate the penultimate index in a test actvity for a Page List called "ActionList" I used: