Why wouldn't the passive hub work?
That would probably work as you explained, but before I started removing fuses off a hub, I'd rather just make a custom cable to accomplish the task rather than dealing with the hub at all.
Without wireless, there is now way to get around running at least one cable to each of the 3 devices (2x LE, 1x Dongle). Using normal cabling, unless you have a splitter of some sort, you are going to need at least one LE with two cables, an IN and an OUT. If it is too hard or undesirable to run two cables to one LE or to connect the LE's together via a direct cable, you can always feed the OUT data back onto an unused pair of the IN cable and break it out elsewhere to go to the second LE.
I'd run a cable from the dongle to the first LE passing by a location central to the 3 devices. Then run a cable from the second LE back to that same central location. On the dongle end, wire the RJ45 as normal. In the first LE, break out the brown pair and terminate it on positions 1 (white/brown) and 2 (brown) of a RJ45 connector. Connect the orange pair as normal on another RJ45 connector. Connect the orange RJ45 to the DMX IN on the LE. Connect the brown RJ45 to the DMX OUT. Go back to the central location where the cables meet. Split open the jacket on the cable that passes through and cut the brown pair. Solder the brown pair from the end that goes to the first LE to the brown pair on the other cable that goes to the second LE. At the second LE, crimp another RJ45 on the brown pair using the same pinout as the brown pair at the first LE. Connect this RJ45 to the DMX IN. Remove terminator in first LE and terminate on the second LE.
This daisy chains the LE's together but there is only one cable going out to each device. This only costs the Cat-5 and 4 RJ45 connectors and doesn't require power or any device other than the dongle and two LE's. This only works in the case of the two LE's, you couldn't connect up another LE using the brown pair, but you could use the same logic to go out to another LE using the blue or green pair and only have one Cat-5 out to the LE's from the central location.