I've had both tables and trough's on my boats. I like the trough much better. Fish doesn't slide around like they do on tables. Turn it upside down for easy gutting, cleaning, gilling, pressure bleeding etc. I made mine big enough to fit very large salmon, Ling Cod, or even chicken Hali's in. If you can, buy or make a trough with a deeper narrow V in it. Keeps the fish much tighter in the trough that a wider angled V and doesn't allow it to slide around. If the V angle is too wide the fish slide around a lot. It's also great to have two drain holes, one at each end so that no matter what side the boat is listing on when you are cleaning the fish the water/blood/guts will shoot right out of the trough quickly ensuring your fish isn't sitting in blood and guts. Make sure the drain holes are large enough for all the guts to go out or else you'll be picking up the guts with your hands and throwing them out the boat which just gets blood/guts outside of the trough and onto your boat.
I also have a two fresh water lines that I quick connect to my fresh water tank that I use for both pressure bleeding and cleaning out the fish cavity after gutting bleeding so that no sea water is used to touch the open meat of the fish with. One is a flexible small diameter line for pressure bleeding and the other is bigger diameter line with a spray nozzle on it.