If your trunk is dry, its not likely to be the coolant tank
Was the tank empty?
The water pump is on the front of the engine on the passenger side, so a leak there could be by the tire
There are several plastic covers on the bottom that can redirect water from where it is leaking
If you remove the front one, its pretty easy, you will need a 10mm socket and a torx screwdriver. You may see where it is actually leaking from
Just be careful as the coolant will be hot and can burn you if the car is all warmed up
There is a very good indy just off Miramar road
Mirage Intl - Porsche parts and tuning
another excellent shop is
Black Forest Porsche/BMW/Mini | Your Dealer Alternative
You could also go to Porsche of San Diego on Miramar Rd. My guess it would cost you more there
I would see if you can figure out what is leaking and if it is the water pump and you have the time, DIY
Both shops are PCA members and may offer a PCA discount
Yo can join PCA for $46