It looks like you've done your homework in terms of making sure the Allure planks won't separate due to moisture over time.
However, the underlayment you want to use by TrafficMaster is NOT recommended and rated for vinyl plank flooring. It is only rated for click-lock and laminate wood flooring.
Therefore, it would lead to issues with your Allure planks and it would lead to failure as well as voiding your warranty.
Cushioned underlayment is not recommended for any vinyl flooring, due to it being already cushioned resilient substrate.
Your best bet would be to install a simple moisture barrier, which is rated for your Allure. It is paper thin and allows no moisture to come through, if installed correctly.
One that I recommend is linked below:http://www.homedepot.com/p/Roberts-...
Use it, and you'll have no problems with any moisture in your below grade floor.