No prob - it takes more getting used to with the ultralight or just plain light gear, doesn't it?
With the Granite Gear pack I have load lifters and such - with the Mariposa, I'm left with the belt and straps and sternum strap. So, I follow the usual sequence of shrugging up with the shoulders and tightening (overtightening) the belt, with the padding centered over my hip bones. When the pack settles on the hips, I pull on the shoulder straps til the pack is against my back and I can feel the weight settling downward. The sternum strap is as loose as I can stand it without letting the straps drift out.
I have done two things - since I have not one but two quilts (underquilt and top quilt that go with my hammock, oo lala comfort!) I have tried each quilt in its own stuff bag side by side in the bottom, and also stuffed both quilts in a larger (Ray Way style, goes with my Ray Way quilt) stuff sack, which is designed to let the quilt loft in the pack. Both JRB quilts fit quite well in the Ray Way sack with room to spare for my down jacket. With two stuff sacks the quilts fill the bottom of the pack tightly. With the one more vertical sack it will get tighter if I pack stuff in on top very tight, but not feel like the seams will burst. Carrying both quilts in the one sack results in a more vertical load and the tarp and hammock will stuff tightly down either side of it. A bearvault solo will fit on top and the lid will be even with the frame top. The rain poncho, day's lunch/snacks, and a bit of fishing tackle go on top of the can in the extension. Filter and other smaller items go in the front pocket.
I'm considering trying the NeoAir slightly inflated (medium, 20" wide) in the pack instead of the Sitlite. Not sure how that will wear on the mattress, tho.