I took my FC to Colonia around Christmas, and back to the bubble again a few weeks ago. Instead of mining it, I set up a buy order of 8,000t Tritium @75k credits before my trip, which was fulfilled by other players within two hours (this surprised me as 75k isn't the highest price around).
I was able to sell 1,000t in Colonia to another carrier for a decent profit of about 50k per ton, and still had about 300t of Tritium left when I arrived back in the Bubble. For mini jumps within the Colonia region I topped up the FC tank by mining in a double hotspot there now and then, 150t in roughly an hour or so. Wouldn't want to rely on mining en-route because I don't enjoy prolongued trips in the black (like Frillop would for example), but getting the credits to buy the Tritium either at premium prices so other players can do the loading for you, or instead buying at the ~50k market prices and load it yourself works pretty well for me.