The best I can do at the moment is tell you to try and use the focus frame, for example set your focus to your pet. There is a focus target frame. Besides that I am a little reluctant of adding more xtarget frames.
Hmmm... there sure was times when I had to re-summon it, but AFAICR it happened between those summons as well.
Bah, I'll be a bit more aware tonight ^^
Anyway, I was thinking on binding my pet-attack key on a macro that would focus on the pet... unfortunatly I don't know how to do that, and to be honest... that seems a bit awkward.
I guess nothing beats a good ol' built-in feature ;]