....in a stable descending turn the inside wing is always undergoing a
downward motion relative to the outer wing. This is one cause for the
inside wing to be at a higher AOA than the outer wing, and one reason
for the resulting earlier stall than the outer wing.

Understood! What I don't unerstand is how much washout plays into this
equation. I would suspect that it would reduce this efffect but how much?

Really good question! I don't know. Since washout is, in a sense, a
relative term -- that is washout produces a lower AOA at the wing tips
compared to the AOA at the wing roots

After thinking about this for a while, I suspect that it (washout)
doesn't matter. After all, both wings tips have an equal amount of
washout and so the net effect cancels out. The lower wing tip will still
have a higher angle of attack than the upper and will still stall first.
In this case, the effect of washout is a (wait for it :-) ) wash.

Tony V.