^ this. You can't really have your cake and eat it to unfortunately. You can have smoothness, but it's not going to handle weight well. Or you can handle weight, but it will be stiff when it's unloaded. I looooooove my 891s probably more than anyone on here (there are lots of haters it seems) but that's because I'm one of the few that actually carries 500-600 lbs between my bumper, spare, gear, tools, sliders, skids, etc.. I had to put 20mm worth of spacers in the back to get my lift back to where it was, but mine rides much smoother now than before adding the weight. I feel I have the best of both worlds because my junk flexes like butter now, but I can also throw an additional 200 lbs. of camping gear back there and it doesn't sag (or at least not enough to notice).
Another option you could try is 890s. They will still handle weight a little better than LCs, but they're not as stiff as 891s. Kind of a good compromise. They tend to sit ~.25-.5" lower than the 891s though so I would definitely recommend adding an additional 10mm OME spacer on top of each one (the spacers are $10 ea. from toytec) to match the height you're at now. If they still sag too much with the trailer hooked up, you can stack two 10mm spacers to get 20mm (which is what I did).
