In order to have two unrelated plugins aligned, on a vertical panel no-less... in the space of one block, you would need to resize one block by 1/2. Then realign the other block. Then nest the reduced block within the aligned portion of the other block.
Doing this with Wifi and sound would be near impossible, as the scalable icon sizing would be thrown off and if you moved a plugin location, your gnome-shell would crash.
But doing this with the battery percentage becomes worse, since the percentage value changes size. In one normal sized padded block, that is fine but in the restricted 1/2 size block, fine turns into a nightmare.
I agree with your assessment that it is not possible. Aside from that you would need to adjust, then recompile the gnome-shell from source just to get to the nightmare stage in the first place.