Has anyone tried a tump line with UL?
It seems to me that might work well when your load gets up towards your pack's limits (e.g. food for a longer trip could do that, or needing to carry a lot of water). If it is set up right, you could vary the load between your neck and your shoulder straps, much as a conventional pack varies it between the waist and shoulder straps.
The following examples are not UL, but they worked so well that I wonder about a UL version.
I got thinking about this because I used tump lines one summer leading canoe trips in Canada -- we tumped canoes, wanigan boxes, duffel bags .... You need to get used to using a tump line, much as you once had to get used to a pack's waist belt and shoulder straps. Once I got used to mine, I would not do it any other way.
Note that professional load carriers, such as Sherpas and other porters, also tump heavy loads.