When I was starting and learning about machine quilting one of the standard remarks was "you don't want it to end up like a mattress pad." But there are mattress pads and there are mattress pads and I think you could be just fine. I would think they would be easy to work with, watch for the weight and stiffness.
I have used blankets, both knitted acrylic type as well as green wool army blankets as battings, as well as encasing entire old quilts with lots of love and memories between a new top and bottom.