My first dubia colony

Hello all! I haven't been active in quite some time but still refer to you experts in my times of need! Jelly is doing great, a little over a year old now! Today I went to a reptile & exotic expo and FINALLY got some Dubia roaches (50 of mixed Male to female ratio)
Ive been wanting to start a colony quite a while now and decided today is the day!

Currently I'm sitting with:
30gal Sterilite tub
100w CHE that sits on top of a mesh screen (about 16in wide cutout on the lid to help with some airflow to hopefully prevent mold growth or too much heat)
2 4W UTH's with foil tape on the sticky side them to prevent melting the bottom of the plastic container
Two large egg flats (ordering more that should be here on Tuesday)
4 sponges saturated with water (hydration and humidity) and two small dishes with dry roach diet
And or course the 50 roaches...

It's been about 45min to an hour and the inside temp is only at 75 degrees Fahrenheit.
I'm not sure what I can do to improve this set up, if it's needed. These are large dubias that are near adulthood, so I don't expect them to breed yet. I want to perfect as much as possible for when they're ready..

Any advice or criticism will be greatly appreciated!

Jelly & I thank you!

UPDATE
By morning the temp got up to 83.6!
Good but not good enough.
I also checked my hygrometer and the humidity in there is no different than the rest of my home but just a few RH%
Maybe the cut out is too large?