Not with a dry pot obviously, but otherwise not a problem with Esbits, alcohol or canister stoves.
All of your ideas can be fabricated. Curious, why do you want to shorten from the top down?
I take off the bottom of the Foster’s can because it is rounded and disproportionately thicker than the sides of the can. The flat cat food can sits well on a variety of pot supports, weighs less, and absorbs heat better.