Hi Steve. Welcome to Permies.
I
think one of the reasons that you might not see it discussed much is because it has been touted as a way to not have to chop large
trees, or so you can use coppiced wood, branches, and trimmings for heat, and use the larger logs for lumber.
That said, I know that batch box designs exist that will take logs of reasonable girth, cut to length so as to fit in the burn tunnel with the door closed. It can be done.
My concern would be that, if you need to fill the box to get a proper burn, and that box is too large for the system or the room, you could be heating much more than is comfortable or necessary, and you could negate some of the efficiency that is one of the biggest draws for those seeking to heat with RMHs.
I would, in your case, providing the large logs can't be used better, cut them to length for a batch-box-style
RMH sized to the house you want to heat. I would then build said
RMH, and perhaps concurrently with this, I would spend time splitting the rounds, probably by hand, with a maul, because it's one of my favourite, most relaxing outdoor tasks.
When it would come time to load the batch box for a burn, I wouldn't have to wrestle a giant round into it (if I went with a design with an open, gravity-fed burn tunnel, the sizing would be even more difficult, I suspect). I wouldn't have to worry about obstructed airflow, or about feeding smaller fuel around the giant log as it burns from the outside of one end to the core. I would be loading the box evenly, with similar-sized pieces, to form a stack that air can move through (well, after I start the thing with kindling and progressively larger material).
As I said, it can be done. I just think it's important to keep in mind what it is RMHs are designed to do well, how it is they do that, and the reason
people have historically split their round logs for the fire.
-CK
A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects.
-Robert A. Heinlein