It depends on what you favor between time, concentration, risk, and total distance.
To avoid generalization, here are the principles I think of around this :
– As long as you don't overheat too much too often (and it can happen in the clipper), using the highest slot size for fuel scoop favors time and distance.
– Some ships use a lot % of their tank in a few jumps (FDL, Corvette...) ; those become really more comfortable with tanks even if it's only for travelling.
– Having tanks reduces jump range and total distance / time. It won't make you Elite Explorer slower nor that much poorer in the end.
– Having a tank can give you more time between scoops, and less risk to accident because of distraction or else, and can let you scoop more on the easier stars and less on the painful/risky ones... not sure you in the end lose more time.
I actually made the travel to Sag A* with a fuel scoop in my Asp, and found it way more comfortable this way (and less stressful).
It let me visit not only refuel stars (KFOGBAM) on the way without worrying at all.
128t may actually be a bit overkill for you alone though (every few jumps, there's an easy star to replenish), and for long range expeditions it might be actually be significant (with a quick look at EDShipyard, it seems like 3+LY jump range, may be a 32t or so on the clipper base 16t could be enough without costing so much jump range).
It would be cool though for being a fuel rat I guess (don't forget the limpets). And thanks for thinking to be useful to other commanders.