The new expansion has an achievement for 100 exalted reputation. So I want to ask if it is possible to have both these reputations on "exalted" at the same time. If yes, how should I farm it?
It is possible, but takes a long time to maintain Steamwheedle Cartel rep while farming rep for the Bloodsail Buccaneers. Also the achievement Insane in the Membrane does not require to have them both up at the same time.
If you still want to do that you should get your Bloodsail rep up to exalted be prepared to kill thousands of pirates.
- Get the Bloodsail Buccaneers up to exalted. Don't care about Steamwheedle for now (it takes much longer to maintain a good rep with both at the same time). Do the quests, kill Bruisers, ... just do what you would normally do.
- Get back the goblin rep:
The pirates near Gadgetzan in Tanaris for example will give you rep for the SC without you losing any Bloodsail rep. You can as well kill Venture Co. and other folks unfriendly towards the SC, but stay out of Stranglethorn. Quests, kills, etc gaining you rep for the SC will lose you five times the amount from the pirates.