Chip
Boat = west marine.
Check the catalog, there are several options available. In your case I would get the oil pan adapters and run a decent size hose (1/2" ID) up the bulkhead.
Add the remote pump with some good fittings and you and leave the pump mounted. Have one hose pigtail to pump oil into a 5 gallon bucket and have a second longer pigtail, maybe with a 1/2" copper pipe dip tube to pump the new oil back in. I use 5 gallon buckets for oil (5 at a time

)
Works for me. When I change the oil on my boat were talking two 6-71's with almost 7 "gallons" each, two transmissions with 2 gallons each and the genset, another gallon.
I have a manifold system I made (you can also buy ready made) that allows me to pump old oil out, and then pump in the new with only flipping a switch and moving some valve levers (1/2 turn ball valves)
The 1/2' hose recommendation is so the pump doesnt strain pumping in cold oil.
My procedure:
pump out 2 engines, pump out genset, pump out 2 transmissions (trans oil is almost always very clean, this flushes the lines)
pump in to the engines, this removes any residuals in the lines, with 7 gallons, the engines can handle anything that might get back in.
Then fill the trans and genset.
I also have this piped with a 20 gallon "oil tank" so that I can top off at any time with just a lever throw / switch flick.
Works good.