After reading these comments, I am going to go ahead and start the pad project as soon as possible rather than waiting for a while. Now this opens up a lot of follow questions.
I would like to tackle this project myself, although I have never done anything like this. Without measuring at all my best guess is that I would need to to build a 3 side retaining wall that is approximately 2.5 to 3ft tall in the rear in order to get the trailer close to level. I have asked different people the best way to go about building the wall using lumber instead of blocks, and I got different opinions. One person told me to anchor 6x6 posts into the ground with concrete and build the walls with 2x6's. Another told me to use 6x6's to build the entire thing, using rebar to stake the base layer into the ground and attach the rest with spikes.
Youtube doesn't have a whole lot of examples of what I'm trying to accomplish, so if anybody has any knowledge of this please let me know.
Thank you for the help!