In the SAR world, there's a bit of compromising between performance and endurance to be done. For instance, if you are going to rescue someone from a mountain, you don't want much fuel on board, but if the position is uncertain, you need enough fuel to find them first. If the task is a search, you need to establish (based on weather and availability of other assets) whether you want to arrive with plenty of fuel to give you a worthwhile amount of time to search, or arrive with not much fuel to allow you to deliver MRT quickly onto the hillside (takes a long time if you can only move 3 or 4 at a time!). Throughout all of this, one has to remain aware of distance to the nearest fuel site, what time that fuel site is open, how easy it will be to get there based on day/night/weather etc etc.
In the RAF SAR Force, we used to hedge our bets somewhat and have the aircraft approximately half full - 3000lbs of fuel would give nearly 3 hours endurance (enough to get to the job and arrive with enough performance to winch, get the casualty to hospital and find a refuel site in most cases). There was always a bowser on hand to top up the aircraft if a longer-range job (or search) came in. If one wanted to take full fuel, the aircraft needed to be stripped due to the weight of the role equipment. Inevitably, this took a bit of time but a lot of the stuff could be removed fairly quickly - it was only taking the seats out etc which took a bit longer, and on a proper long-range job the crew would take time to check the fuel plan before launching so the engineers had time to strip stuff out anyway.
At least one unit used to reduce the standard fuel load in the summer because the mountains were on the doorstep, whereas other bases were further from the hills so would burn more fuel getting there. If one arrived on scene without sufficient performance, there was always the option to chuck fuel over the side, but it's not a popular move given how many SAROps take place in National Parks...I only saw this done once when a visiting Captain gassed up the aircraft to MAUM ready for a good long training sortie all over the Highlands in glorious summer sunshine, and we promptly got scrambled to two cragfast climbers who had made it almost to the top of Ben Nevis...cue dumping of fuel most of the way down the Great Glen, and more on scene when we got there and tried to hover and still ran out of power
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