This is now a full 98" deep and 2" deep. That’s 1" longer than 4x8 sheets, so you don’t have to run your sheet to the edges. It’s best to move a bit away from the edges because nails/screws tend to crumble the MDF.
I want to give it a bit and make sure everything’s working and staying in place before leveling it. It’s pretty level as-is though.