Yea, being able to just plug into the toad's lights is certainly a time and frustration saver.
There are several ways you can run lights to the toad. You can do as you did, with a diode kit, or you can run a separate set of wires to the tail-lights with extra bulbs attached inside of the bezels (what I did), or magnetic lights, etc.
I had originally thought of adding a bracket that would attach to the trailer hitch mounted bike rack, so that it would have arms that extended left and right to attach temporary wireless lights (or permanently attached lights), but like you did - I ended up with a more permanent solution.
One risk though of using a diode kit is some of the newer vehicles have sophisticated light systems that are actually networked (CAN-BUS) rather than simple DC wiring. In those situations you could really mess things up by using a diode kit.
There is no best way, other than the way that works for your vehicle, and is the least laborious. One person that does a lot of RV YouTube videos has an old Suzuki Samuri with a fiberglass top. They literally cut out the bottom of a couple of Tuna cans and screwed them to the fiberglass top to have a bit of steel for the magnetic lights to attach to.
While I would never do something so "crude", it worked for them, and that is what matters.