In case anyone wanted to know what happened, I was managing to whittle away at the lone hostile with my 2 8kt jump ships and 3 4 kt pickets by spamming missiles at way points and hoping the missiles would get a thermal lock. He wasn't intercepting anything, apparently he had no missile defense except raw, blistering speed (8,000+ kps until I damaged his drive and dropped him down to 681 kps.) I must have damaged his magazine or something because he stopped shooting. I foolishly assumed he'd run out of ammo and decided to move in and rescue the life pods from the jump ship he'd managed to take out. Over the course of the next few minutes I emptied the task force's magazines but my luck ran out: none of the missile salvos managed a lock. After running out of ammo and scooping up the life pods, I made for the jump point.
A few minutes later he apparently finished repairs to his magazine. Considering I go very liberal with the CIWS and he was only firing 4 missile salvos, it took a bit of doing, but he eventually slagged every last ship in the task force.
Now that I know I can hurt them with enough salvo density and I can, for a while at least, stand up to return fire, I'm emboldened. There will be a new expedition as soon as I can get a decent sized task force refit with active sensors and perhaps even a load of the new and improved missile I've designed.