My apologies on the previous reply, because I did not notice your reference to the REAR landing gear. Those are not usually called landing gear. Stabilizers or leveling jacks is what those are called.
It might be good if you could post a photo. You are right to be concerned about them, especially on the rear. I like my jacks to be retracted far enough that if I drag my rear bumper, it is my bumper that will drag and not the jacks getting torn off. However, this does vary by trailer model. And I still suspect that the strong-arms were not installed properly, IF it is the strong-arms that are restricting the jack travel. You should get full jack travel, with or without the strong-arms.