[T.G]

Temp and resultant humidity fluctuations are typical for a home refrigerator. Unless they happen a lot or are very drastic in nature, I wouldn't worry about them.

I would keep the handling of the meat down to a minimum if possible.

It would have been slick to have placed a mechanical scale under the tub that holds the meat, tared it for the tub, pan, rack, etc - then placed the meat in the tub and just let it age that way in the refrigerator. No handling necessary to see what the water loss is, just open the door and read the scale.