I’m being honest. But, if your wall tent stove isn’t a house stove, you’ll melt the thing if you get enough air under it.
That’s what coal needs. Air that gets pulled up through it. So, while a wood grate will allow some coal burn in a wood stove, you likely won’t get long, hot burn times. Which is what coal does. It burns exponentially hotter and does so for HOURS longer then a wood fire will be producing any heat.
So, knowing all this, I bought a warm morning coal stove for my wall tent. It POUNDS the heat. In a canvas tent, you can get that tent so hot it’s uncomfortable. In frigid weather. A coal stove will be a stove that draws air up through the fire. From below. Not like a wood stove that vents on the door. And, it’ll have fire bricks.
It’s worth the look. Find a coal stove for your setup. I burn it for my winter house heat. My house is 2100 sqft. My electric bills from November through March never got about $91. And during those months, my house stayed 72 or higher. Most times, 76-77 degrees. My firebox is 100 pounds. I fix the fire once a day.
Didn’t mean to get so long winded. But, it really improves wall tent camping. And, it’s important to know what makes coal worth the effort to burn in your tent.