Yep,
I'd go with the last tip too. If you really want to figure it out, you just going to have to get your little ohmeter tool one nice day, lay it all out and one-by one, start picking circuits until you find a significant spike in one that shows a large difference. This way, you dont have to keep jumping your battery. Your neighbors will frown the more you do this jump thing and gives crooks an impression you are always away. Bottom line is this shouldn't happen even after a month - trickle current or not. We are talking of a big battery probably bigger and much heavier than your head not a little 9V cartridge. I came back after a month of WINTER and started up my bimmer with no prob. Just crank, a little sputter due to the fuel rushing through the dried chambers and the pistons were firing!
So you need to fix things. good luck though