I have and use a Battery Tender and have used it for 5 yrs on various bikes/cars. Love it.
As for tracking down the battery drain:
1) take a low amp fuse and stick it in one of the blower motor fuse slots and turn on the blower, this will blow the fuse.
2) remove each of your other fuses one at a time and stick in the blown fuse. There should be bare spots at the top to access the pins on the fuse w/ the DVM probes.
3) use an DVM set to mA and check the draw of each of your fuse locations. Most will be "0", some will have an expected small draw but you should be able to decide which circuit the excess draw is coming from.
Mine's in the console/radio area but it takes 5 - 7 days of no use to draw it down.