Looks like you had a great day on the water and have some good eats of fresh halibut. I'd like to share what I have learned fishing for the big flat fish in Cook Inlet and Prince William Sound, AK. I fish from a 2016 R-27C with a bimini and limited deck space and will use a harpoon on any halibut over 20-25 pounds for three reasons. First, it is more secure than gaffing the butt and avoids getting someone slapped by a flopping halibut. Second and probably most important, it reduces the mess on deck from a bleeding, slimy flopping halibut. After harpooning the fish we let it calm down until we can get it safely up to the swim platform where we cut the gills and let it hang and bleed out which makes for much cleaner filets when the time comes. I've made some strong 'stringers' out of 3/8" nylon and after the fish bleeds out we transfer the fish onto the stringer, in the water before removing the harpoon. So far not a drop of blood or halibut slime in the boat. And third, we let the single or multiple fish hang on the stringer while fishing to keep them out of the cockpit and under foot. When we are ready to move, we haul the butt up onto the swim step until we reach our next fishing location, then back into the water for cold storage. the only time we bring them into the cockpit is at the end of the day headed to anchorage or home or if we are moving a fairly long distance.
I've built an aluminum frame which mounts on the swim platform over the propane locker where I mount a very, very large cooler for block ice in 1 gallon plastic bottles(last years antifreeze) and filleted fish. The bottled ice keeps water away from the filets. My son is relegated the job of filleting the days catch on the way into anchorage/port with a filet mat on top of the cooler. We've found we can fish and shrimp for 3 days keeping the harvest in good shape until we can vac pack and freeze onshore.
Nothing worse than dried halibut slime on your back deck!
Stay safe.
Bob