Traditionally in TTRPG space, not all Trickster clerics get Deception because it's not needed to trick people. They simply use magic to improve other people's ability to play tricks.
I partially agree with the proficiency in Stealth thing and here is why - Most players who run this class always start out as Rangers to get that proficiency.
Your ideas are more about improving SH's starting proficiencies than the actual class itself. Deception is part of her trickery style because she is a disciple of Shar. Tav on the other hand may be content with Performance in place of Deception so he can distract NPC's from Astarion exploring their pockets.
Disguise Self already works as a Ritual for all spellcasters and Trickery Domain clerics already get that spell for free. Even EK and Sorcerers can cast Disguise Self without burning a spell slot, which I am pretty sure is a bug because neither of those classes get Ritual Spellcasting as a feature.
I do agree with Blessing of the Trickster though - even in TTRPG a few DM's allow that skill to work on self, but they limit the activation of that ability based on a number of times equal to proficiency modifier per long rest.
Overall, I got to say, this is not the direction I was hoping this thread would go, but some of those do make sense for SH.
Thing is, this thread is more about improving Trickery Domain for TAV and not about how the backgrounds available for Tav don't fit the Origin Characters like a glove.
Trickery is literally about deceit. It's in the description. Having deception as a skill is more than reasonable, whether that be for Tav or Shadowheart or anyone else who wants to explore the domain.
I certainly think it's a lot more appropriate for any devotee of Trickery than, say, gaseous form. I'm happy to agree to disagree.
As for some players starting as a ranger... I don't think that's at all relevant to what's included or not included in the Trickery domain. I care far more about what the domain offers me in terms of trickery potential than I do how someone else decides to multiclass.
It's good to hear Disguise Self is a ritual spell. I typically use the Mask of the Shapeshifter when I want to use that spell. I don't think I've bothered casting it from a spell slot in a long time.
