none of this comes from my original thought--
We currently have--
For exit plan:
We get into the circle formation. Once we are surrounded, engaged in heavy melee, etc., Kareth Abundant Step with two people (must be within 640 ft. of destination) and Xath teleports, using the shoes, with two people or she uses Dimension Door with two people (must be within 800 ft. of destination).
Both groups have the destination of Hywrl where we will fight some more.
Thane is kept in reserve for FUBAR.
For entry plan:
Ohtar can drop us off 60 feet from wall --lets see if the little archers under the woodshadow banner have learned enough to be any good-- and then he returns to Hywrl (for further guarding/protecting Dorn).
Ohtar can only carry 800 pounds, though. With gear I have no idea what our average weight is, but I am sure it is more then 133 pounds. Kareth can run as fast as O. can fly (80 ft.), but I am not sure if this would place Kareth in the fatigued category. If he could run the distance without fatigue issues it would mean our average weight could be 160 pounds.
We can also, if it a short enough trip, just stick someone in the bag of holding... not exactly the optimal way to travel I know, but no chance of fatigue.
If this works in anyone else's mind then we do not have to waste coin or magic on getting into place.