A few posts ago you were whining just like BRF "I can't catch anything on the Caney... where are all the fish?? ... what am I doing wrong??" and now you're offering sound advice!? Where did this come from??
congrats! You're not only addicted, you know what's going on and how to explain it. Very gratifying...
Now for some specifics.
The 12' that Grumpy was referring to was for some specific areas along the Caney's course. Lancaster is not one of them. Most of the Lancaster area is way too shallow (when it's wade-able) to use anything over 3' on your dropper - even up against the bank. So 24" to 36" in the Lancaster area should work just fine. And, yes, yarn indicators are move able so start at 24" and adjust from there.
The area below the bluffs (and just before the bluffs if you're drifting) is full of some very deep, slow pools where you can extend your dropper to some incredible depths. There are a few killer browns in there, but there's also a lot of deep hidden structure there so you've got to be pretty careful.
Congrats, Trey! You're now suddenly giving back and I think that's great