My room temperature is about 18°C / 65F. After more research I planned on using a heat cable on both sides, more concentrated on the warm side, or add another heating pad. If necessary I'll add a heat lamp, but I fear getting problems with the humidity then.
If I use this substrate, will this keep the humidity levels up?

I checked for the Antonius planks and they should be ordinary Melamine planks, with which I saw lots of cages being build so far, so they should be alright.

Thanks,
Charel