You had the right idea for testing but use a multimeter instead. It will give you better results. Same drill...probes inline with one of the battery cables and have a buddy start pulling fuses, one by one, and monitor the difference in current.
The dim dash lights make me scratch my head a bit though. This would mean a residual voltage coming into the bulbs as there are not too many grounds in the vehicle that are switched. Hmmmm...
I'll have to give that one some additional thought.
I put a test light inline with the battery and found that when I pulled the int lights fuse under the hood (50amp I beleive)
I missed this part before. A 50 amp fuse would not be only for the interior lights. They would probably drain 10 amps...maybe 15 on a bad day. That circuit is for much more than just lights so don't limit your search to them only.