45% is a bit low but not a massive issue. This would need to be increased for a shed but that is about it. The thing I noticed is what looks like a very large gap between the tub and rack. i have watched a snake as big around as a large mans leg fit under a 1.5 inch gap. I would be concerned about escapes or at least attempts...

Paper actually will decrease humidity at least when it is fresh if you are having issues it may not be the best choice (coco or cyprus holds much more) The easy option with a rack is just humidify the room to 60% and call it a day however.