Keep in mind that class registrations have more or less already occurred, and many classes are impacted (full).
What I think that means is that you will need to accept your Overland Experience Pkg subject to the classes the seller has already chosen. Probably, there is some wiggle room to move around a little, but I believe many classes have significant wait lists.
Disclaimer: I am not related to OVEXPO, and I probably don't know what I am talking about. I am simply making an observation in the spirit of being mindful. Or whatever.