I actually did all four steamwheedle reps first to fully exalted as I never had any intention of going for the insane title. It was only after I realised how damn easy it was to now raise DMF rep that I considered becoming Insane lol.
So it is from personal experience that I suggest going for Bloodsail first, I understand your predicament though and as you are so far in then it would be silly not to do Steamwheedle first. However I really think that once you do drop your rep to hated with the goblins then its a really good idea to raise it back to at least neutral with the dreaded Goblins, they can be evil monsters and believe me you will forget they hate you until you visit them and they net you and murder you lol.
It isnt hard at all to do, just time consuming, I went from fully exalted with all 4 steamwheedle reps, to 1/36000 hated and honored with the Bloodsail, then back to fully exalted with the Goblins all within about 4 days.
Stupid really but I just can't stand my reputation bars not to be full for any faction! Maybe I suffer from OCD :P
GL with your grind, and remember to place your Guild Standard down for the extra rep