With the top up there is quite a bit of room in the trunk - more than plenty for two people on a long weekend. Top down you definitely need to pack light and make use of soft sided luggage - duffel bags for sure.

I recently did a track day weekend and travelled both directions top down. Now, I was by myself but even with the top down I managed to stuff in a folding chair in it's own stuff sack, my suitcase, my laptop case (which is fairly large in its own right), a small cooler (6 pack size thing) and an additional small duffel bag with my detailing supplies. The only thing I needed to put on the passenger floor in the cockpit was my helmet bag. Had I travelled top up then everything would have fit in the trunk with plenty of room left over for another person's luggage.