It took a few nights, but I'm there. I am running two clones (one's my old main, the other is new) through all of the Solomon Islands stuff.
The build I'm using most of the time can be found here: http://wordpress.tswguides.com/my-fi...-with-bladear/
I like it because you can do 99% of your DPS and self-healing without worrying about which direction you're facing. I like prancing through the beaches of zombies and Draugs, twirling my blades, and looking back to see a beach full of loot. This build would conceivably work with any number of characters while questing.
Movement: I just made a copy of the old FTL DPS set of keybinds, copied that to my TSW character set. Deleted W A S D and all of the movement keys (you don't really need those, with follow being persistent and all) and, admittedly, my slave gets caught in a lot of AoE. The /follow thing is a pain, because I can't get a hotkeystring to work, so I end up manually going over to the other window and typing /fo and hitting tab to finish the command. I also set it so when I hit F1 it'll send an F1 to my main window, F2 to the slave window. When I hit F2, it sends F2 to the main window, F1 to the slave window. That way, if I'm duoing, it'll always have both target the same person. This makes the assist command great, and also if I actually need to worry about healing (like farming a nightmare mob) I can just have both characters spam Anima shot while targetting the one in need.
Sharing quests is faster than actually getting the quest on the slave. Many quest objectives update for both windows (Even if the quest window is "Go get a can of gas", but you have to constantly watch because some don't.
That's it so far. I'm off to approach Egypt.