In the car user manual, the functions of each fuse usually come, as well as the position of the same and the amperage, eg: nº6 10 A, right position, registration light, nº7 10 A, left position, console lighting ...
if you have removed all the position lamps, (not only the rear) and continues to fail, look to see what more things that fuse does, eg, enrollment light, light, lighting. All consumption of that fuse continues to jump, you will have to look at the cable hoses looking for some friction or peeling in them. (Unlikely because the hoses of the pilots do not go in mobile parts such as the doors and the trunk, but it is good to look anyway).
Another thing that can happen to you is that some pilot's cap has been melted or screwed out and despite having no lamp, it is short.
Pilot connectors can also give war, but I don't think they are because the paste is usually the "fair of light effect" (when the dough fails) or that some lamp does not turn on despite being well (when a terminal fails).
All the best.