which 4 link for towing?

[Richard]

Other than a watts link setup eliminating the side load on the link bars there is no difference from a double triangulated 4 link. A single triangulated setup will introduce more rear steer than the previous. Note that excess rear steer would most likely not be noticeable except in high articulation situations. Triangulated setups are used on monster trucks. 10,000lbs, 1,000hp, super heavy tires and they do crazy things with those trucks.