I'm going back to a previous life but our ASW SK had 5,300lb of fuel at 1,000lb/hr, and the SAR machines sold to Germany, Norway and Denmark had a full centre tank where the sonar well was, increasing fuel to ~7,000lb. In my book that gives 6+ hours, and as to payload then you will burn off 40% of your fuel to get to the scene: there's 2,000lb at least!
That was with underfloor tanks, which made no intrusion into any cabin or cargo space nor had any extra effect on CoG.
Or don't the current SAR Sea Kings have the full fuel capability?