Bearer thralls are useless atm, we all know that.
However, what about making them vendor thralls?
I can put a vendor thrall in the jungle with a small shop, selling brimstones or coals since they are not easy to get there, putting tons of such items in the thrall, and asking some specific resource in return (for example, steel bar, volatile gland etc that have greate yield in jungle area, maybe even black lotus).
You can return later to gather the resource the thrall aimed to get, and restock him/her. The trader place will fill its decay timer a bit if trading happened.
They still need more inventory spaces, but this implementation will be way better than the current bearer thrall