You're the only one that can make the decision to keep or sell your Boxster.
Personally, I would keep the Boxster, but only if you can realistically pull it off. If your going to need more than two seats, and the two trunks on a regular basis the Boxster wouldn't be practical. But if you only need the extra space to move, I would try and keep the Box.
There is nothing better than driving down PCH with the top down.