My summit has been out of commission for the better part of two months as I worked on the upgrades and waited on the parts to arrive.
Rear steer - 4WS
I owe the basics of the rear steering to Quandiak and Brasher. I originally attempted to make the rear steer from a bi-pivoting harness structure but the hole and screw tolerances allowed for too much play in the wheels. After several attempts I eventually settled on a stock erevo one arm steering servo saver set up and a hobbywing 208 oz torque metal geared servo. The servo is strong, and the turning radius is incredible. The truck is roughly 2 feet long and the turning radius is less than 3 feet, even smaller in loose dirt. I can actually run circles around myself . (video to come soon). If I put my foot on the gas while on a smooth surface I think I can almost turn in the same spot. I used y harnesses to wire all three turning servos together and thus far it is working well - sorry no crab steering yet.
Rear steer ( 4WS )
other parts are still in progress