You don't need to fiberglass but a good marine-grade paint is a must as well as a quality drain and you would do well to add two 'wings' or wet shelves to the ends, sloping inward with low walls on the sides and ends. A back splash that is able to support water-filters is always good too. I hate trying to bend down to check on these, much less change them out from a tight space.
The design I'm remembering had these wings large enough that a large round, white plastic printwasher could set on it without overhanging and the unocupied shelve was very useful for setting things up out of the way instead of inside the sink, ie dish-racks for drying reels, tanks, etc.
I also suggest you get design the sink with a saloon type footrest as long hours at the sink can add up to a bad back. Use a round bar, not a 2x4 or other box shape, it's important to your comfort. Home centers sell thick, long round wood poles that will work or you use some common steel pipe. If you plan on using the space under the sink, next to the floor, you can always put the foot-rail into brackets that it can lift out of.