Hi Patrick, for an email send you shouldn't need to have a landing page set up... Do you want to just calculate at the end which email performed better, or do you want the ability to see which will perform better based on a send to a segment of your database and then send the winner to the rest?
If you just want to calculate at the end, I'd suggest 2 separate send smart campaigns, one for each subject line. You can split your database 50/50
using these directions, and then send to each of the two lists.
For the challenger/champion style, that's where the Email Programs shine. There are plenty of articles on
using them here.