Despite The Mrs.'s seemingly generous offer, I ended up doing low voltage lighting today. I tore out all the old stuff and started over, cuz the previous transformer had melted for some reason. I suspected it was perhaps a short, so I made sure all the lightbulbs were out of the old fixtures, and I measures the resistance from the supply to the ground wires.
It measured 475 Ohms. Now, for those of you who do not have an electronics background, that's waaaay too low to be a normal open circuit. So I decided to replace the wire in addition to the fixtures and transformer.
Later, as I was tearing out the old wires, I discovered about four more light fixtures that had been overgrown by ice plant (little spot-light jobbers, not the tall lanterns I had known about). Perhaps they were the reason I got a low resistance. It certainly in range for having a few 10W bulbs connected. But, whatever. I got to see how the previous owner had done junctions - just twisted the wire together, wrapped it with electrical tape, and buried it. That's asking for trouble. I bought fancy silicone-filled waterproof outdoor wire nuts.
I put in four carriage-style lanterns (one can be seen in foreground rock-pile of the photo) and one post-style light (seen in background between steps and dwarf spruce tree). It all went smashingly, except I ran out of time before I got to bury the wires.
We had little lamb chops for dinner. A great deal at Sam's club.