Those photos show much more. The first posted photo didn't show the open front. Nice looking cage.
Hmmm... with the whole front being wire, heat can escape more easily. Here are a couple thoughts I had from seeing your photo.
First, please do be careful having a blanket draped over the light fixtures. That could cause a fire hazard. I don't think the blankets should be touching the fixtures themselves.
If the 3rd level is not in use, then perhaps you can hang a CHE inside the cage so that the bottom most part of the CHE is even with the 3rd level. (Otherwise you could try putting it on the cage top, but I don't know if it would be as effective at that distance.)
If you are still having cold temps, I'd suggest not waiting the 4 weeks for the thermostat. I'd suggest going to a reptile store and getting the thermostat and connecting it to a CHE. That way the temp can be regulated and consistent. You set it for the preferred temperature and it will come on as needed and go off when it reaches the desired temp.
here with my new Mecki-- born 2/12/19