This enclosure looks good. Are you using a CHE and UVB striplight?I built a big closed chamber tank. Holds humidity at about 85% no problem. And temp is on a thermostat so it's always steadyView attachment 211007
I set them up the same way. To get the humidity balanced you just need to have the correct water surface area amount for the enclosure size.Once you get it dialed in it runs its self. Set timers and thermostat check it often for humidity and temp to start with but once you get it right that's it. The water bowl actually makes the humidity perfect (he walks through and some spills out) with out having to dump extra water in substrate.