I like the idea of using Skeptics to reduce the Sloth in your own provinces, but that requires you to zero the Dominion, right? Not a very good idea, to me.
From my own experience with GE Arco, there are a couple of ways to go about playing them, at least early game.
One is to focus on Wind Riders. They ARE a good Sacred unit. The reasoning behind it is that you are only able to hire 3 or so Myrmidons a turn at the beginning, and you can hire 2 or 3 Wind Riders a turn, if you do it right.
Another is to try to mitigate the damage done by the Sloth scale. I normally play on Rich (no matter who I play), which certainly mitigates the problem. The other idea is, as others have said, pick a high-admin castle. Let me give you my 'standard' Pretender for Arco, standard or Golden Era.
Lady of Fortune
Water-4, Nature-4
Order-3, (Sloth-1 for GE), Growth 1, Magic 1
Castle Fortification
6 Dominion
(Note that you have 40 extra points in GE to play around with.)
This gives access to the Nature rituals (Gift of Health, etc.), good events in whatever province the Lady is in (which makes it more palatable for her to site-search), and actually a credible SC later in the game. If used to site-search, she's finding all of the Nature and Water sites, which are both useful. Nature gives you gems that you'll need for the Nature rituals, and Water gives you gems for Clams.
You also gives you a plausibly decent Bless effect. Taken together (and assuming you Berserk), you get a +1 to ATT/DEF/PROT/STR. While you can have the unfortunate problem of berserking Priestesses, that problem is minimal, IMO.
Anyway, just some ideas I had.
Scott