If your having issues controlling humidity, add some substrate. I like coconut husk substrate, but other things will work. Dubia like to burrow...and a damp substrate (on one side) will provide all the humidity they need.
Does this make cleaning the bins harder? Yes it does...but you can go longer between cleanings when using a substrate. A trick I use is to have whats called a "rearing" bin. When I clean out a bin full of roaches, usually the really tiny roaches are left behind...along with all the waste and the substrate. I take all of this, and put it in its own bin...the rearing bin. I then wait a couple months for the small roaches to mature, and sort them out. You can now dispose of the waste....I recommend a compost heap.
The process then starts all over again.
Another option is what classic guitar owners use to control humidity inside stored guitars. Take a ziploc bag, and using a hole punch, put numerous holes all over the bag. Then take a large damp sponge and place it in the bag. You then hang this bag on the inside of the roach bin, either pinned to the lid of the side. Re-wet the spong as needed...this should help raise the ambient humidity a tad.
For heat, simple add an overhead heat source such as an infrared bulb, or CHE. Stick to the 40-50 watt range. More information can be found at my website.
Cheers