GL :thumbup2bet, do you have a test light? If not get one. You have a draw.
Since you have two battery's take the positive end from the battery off the starter relay. Next put the test light on the cable/wire and the other end off the relay. The light should light up dim due to power to hold radio memory/clock. If the light lights up nice and bright (like it would if put across to check the light on the battery), then you have a draw. To isolate this draw, while test light still on the two places for test above (if you got to get someone to hold it, do so), start pulling fuses one by one until the light goes out, or back to dim. Once the light dims down, you've found the circuit of the problem. Next find out whats on that circuit and start examining any potential problems. This will tell you which fuse to remove during your parking so the batteries don't go dead until you find the real source of the draw on the circuit.
x3i hear all the time that a bad solenoid would drain the battery and its usually the last thing people check when they have this problem