what are your temps? hot side, cool side, ambient? I think u achieve can 80degree cool side without a heat lamp. i have two BP's in separate 18gallon tanks and have not been using a heat lamp since winter i have my furnace on.
u can add a second water dish or another hide with damp moss to increase humidity. i add this to my BP's during shed, but also keep some damp moss regularly in their enclosure anyway.
the other alternative is to spray/mist regularly or switch to a fully enclosed enclosure/tub.
edit: running a heat lamp sucks up moisture/humidity quickly. running 2 lamps will even neutralize the effectiveness of a humidifier.