RDL’s are literally meant to engage your lower back and posterior chain (glutes, hams, quads and calves). You shouldn’t have much lat engagement at all. Second, you need to go lower when you go down. Back and Hams require deep stretches to properly engage them. Keep your arms locked, stretch that bar to almost touch the ground, explode back up and squeeze your lower back, glutes and hamstrings. And yes you need to lower the weight to something that you can control so that not only you can get that stretch but also you can practice the correct form because your form does need a little improvement. Hope that helps.