I purchased a 1983 San Juan 28 this spring and have been trying to get everything up to speed. It came with a bilge pump located by the keel bolts and I installed a low profile pump directly under the Yanmar Ym15 which is the low point by the engine.
Found some leaks on topside and had to replace the shaft and installed the PSS dripless systemic the shaft , I really recommend this, bilge and boat has been bone dry all summer.
I find it unusual that there would be no bilge pumps?? That is something that should be installed no matter what. You can have drains through the stern for pump out rather than mine which are just by the water line on the stern.
I typically use a portable icebox in the quarter berth rather than the built in model but that was piped into another cockpit drain right under the engine.
Other than that, I love the boat, it is a real hoot to sail and goes well in all conditions even in the waves.
There are many San Juan owners up in the Washington area as well so you will be able to get many helpful tips on these boats.
Hope it works out for you...
"Knotaklu"
Vancouver Island