I like to open and leave open my doors at car shows. With the T-Tops removed my car shows well. I remove the battery terminal to save it. My question is "is there another way to keep the lights off? Other then remove the lamps.
Pop the dome light fuse. You'll most likely lose your radio presets and clock though.
If it's something you do often, get a couple 1/4" spade connectors, some wire, a switch and an external fuse holder. Then you can toggle a kill switch.
I've seen a bar installed between the door and the jamb which allows the door to be opened part way but prevents someone from easily entering the car. I don't know who sells them or how easy it is to install.