You can get a reverse flow hot enough to sear your meat.
Just get a hotter fire going on the box.
As to building the fire on the plate, I'd think not.
In a reverse flow there's really not enough room to build a fire between the plate and the cooking grate, well maybe remove the bottom grate and just use the top, if you're adding a top grate. But still I wouldn't do it in mine.
Arms discourage and keep the invader and plunderer in awe, and preserve order in the world as well as property... Horrid mischief would ensue were the law-abiding deprived of the use of them. Thomas Paine