If your popping fuses, your shorted out somewhere in the wiring. A bad ground would not pop your fuse, the lights just wouldn't work. Light sockets can go bad. Try disconnecting all your sockets then see if the fuse still pops. If not, start reconnecting each socket until the fuse pops. If the fuse pops with all the sockets disconnected the problem is in the harness somewhere. Rear lights usually feed from one side, then crossover to the other side. Check the crossover harness for shorts.