Pet Tethers was a visual option thrown out, but another possible (and potentially less intensive) solution would be a /targetleader (name pending) command. You can /assist an enemy to find out who it's targetting if it's otherwise not apparent (this does have strategic implications, Proto-Ultima says hi), so the framework potentially already exists to implement a command which will change your target to your slept avatar's auto-assist. I suppose it depends on whether or not a specific pet's "master" is easily accessible to the targetting system.

I don't know if it's worth their time, but it does have current applications, has the potential for future strategic applications (content dependent).