Some high tech support ship options:
1) As mentioned, a low sensor profile ship like a colossus but with reduced cargo capacity, increased burn rate, and perhaps better shielding. Notably more expensive, best used for smugglers
2) An capital sized exploration ship with high fuel capacity, built in surveying and salvage gear, improved sensors, and perhaps a ox style burn rate improver... but with quite high maintenance and limited combat performance
3) A fuel tanker with less fuel capacity than the prometheus but with both a nav system and a system like the ox, so it speeds up your whole fleet
4) A ship that slowly generates fuel on the fly. Not enough to sustain a whole fleet, but enough that you might have it for emergencies, and over time it would pay for itself (but that would take quite a while)