I do all my own maintenance on all my vehicles. However, this is my first Porsche (2011 Spyder) and mid engine car. How much access, if any do you have to the top of the motor? I have a lift in my garage so access to underneth the car will be easier.
Take a look at this Article: Boxster Engine Compartment Access - Articles which should give you an idea. I'm not sure how different the exterior access is with the different roof and speed humps in the Spyder, but the actual engine compartment access should be about the same.
Luckily the Spyder will have easier access... from seeing it in person, it looks as though you just remove the foam piece and have access to the engine cover, where the normal boxtser has more steps to get below the auto-top (as in the link).