I dont know if it is possible without having to completely redesign the UI, which LOTRO wont allow. WOW allowed a great addon that showed all the bags in your inventory in one large bag.
As you've already surmised, the current answer would be "no, not possible". Whether it may be possible in the future ... we can only wait to see, and hope.
__________________ "My friends, love is better than anger. Hope is better than fear. Optimism is better than despair. So let us
be loving, hopeful and optimistic. And we’ll change the world."