Yes, inside the riser temperatures are the hottest, close to or over 2000°F
The Batchbox core runs well over 1000°F
Without insulation, your metal stove will warp.
Batchbox incoming air is not restricted; they are run wide open to burn hot and clean.
Most box stoves do not have a large enough air inlet from the factory to feed a batchbox.
By not building to specifications, not running wide open, you will have a normal creosote-making, smoky wood burner.
If you are looking for an RMH wood cook stove that burns super hot and clean, then you should investigate Walker stoves.
https://walkerstoves.com/
Matt developed a riserless core RMH.
He has many options, but his tiny cook stove or his large cookstove might be more to your liking.
Think of an RMH as a top fuel drag race engine.
You could put one in your wife's grocery getter, but it would not be easy, and it would not perform as well as it did at the race track.
Soon, it would carbon up and quit running...