NeverarGreat said:

I've realized that there's potentially a major problem with omitting the end of ANH and a lot of the Hoth material: these are the only times when Han demonstrates his friendship with Luke, first by returning to help in the battle of Yavin, then in searching for Luke on Hoth. This is a problem as Luke's major motivation for leaving Dagobah is that his friends are in danger.

This is true. Unless his reason for leaving is the death of Yoda? Instead of ESB Yoda trying to disuade Luke, ROTJ Yoda tells Luke to go confront Vader. It doesn't matter from Han's perspective since he actually has very little to do with Luke after they all leave Hoth in the rest of ESB and ROTJ anyway.