Planning A Desert Terrarium For Ironclad Beetles

Asking for advice and tips on building and maintaining an arid/desert terrarium for ironclad beetles. I have a lot of experience with planted aquariums but have never attempted a terrarium before. Details on my plans below! 👇

I don't think I want to complicate things by going fully bioactive (with isopods, springtails, etc) but I do want to have live plants and optimal substrate/terrain for the beetles. I live in the desert of northern Nevada and I can legally gather a few buckets of sand/rocks straight from the source. I can get good, clean sand from true sand dunes, or more corse decomposed granite, but what is really optimal for the beetles habitat? What should I avoid when it comes to gathering rocks/wood for this kind of setup?

I'm hoping that I can place my terrarium on this west facing windowsill. It gets an average of about 8 hours of direct sunlight during the afternoons, and I've successfully grown cacti and succulents in this location. We have a very arid, dry high-desert climate. Humidity is usually below 30% and rarely rises above 50% in winter, indoors it's even lower. My biggest concern with the window placement is the cold. We get outside temperatures well below freezing, so I plan to add a lot of heating elements to the setup to ensure the right temperatures.

I've landed on this Lifegard 6 gallon bookshelf aquarium because its the perfect fit for the space. I was thinking of installing a heating mat under the substrate to keep the entire enclosure above minimum temperature during the night. Then also having a heat lamp on a daytime/nighttime cycle to bring temps up to an optimal high on one side of the tank year round. Does this sound like enough heating to keep them warm next to a cold window? How do I set this stuff up with the proper timers/thermostats to make sure temps stay in optimal range?

When it comes to planting, I want to design the scape to include some small, nested terracotta pots built in to the substrate. This way I can conveniently remove the plants and give them a good watering without compromising the humidity in the enclosure. I also plan to use some air plants and anything else that that can be easily removed for watering. I love keeping cacti and have a big collection of potted cacti/succulents. But I'm wondering if any spiny cacti can be dangerous for ironclad beetles? I can imagine them maybe getting stuck on the spines and being unable to free themselves. Any suggestions for my plants list would be much appreciated!

And of course any specific advice anyone might have on caring for the beetles themselves. I'm reading up on caring for BDFB and all their needs. I want to be well educated on them before I begin this build. I know from aquariums that jumping in to keeping a new animal can be difficult, and I want to avoid any unexpected pitfalls.