Buiding a Wood Stove / Insert

I've posted here before about a small rock cabin and our heating issues...With winter coming, I would like to get a stove or insert soon. Here's the old thread:
https://www.hearth.com/talk/threads...l-cabin-need-advice.91005/page-2#post-1193579

And here's my new idea: I can buy a 4x8 sheet of 3/16" steel (last as long as I want it to) for $120 from a local scrap yard that orders in metal on request. I have shops in the area that I work with that are willing to cut the sheets as needed. I'm handy (sort of lol) with a welder and can do most of the labor myself at home. What's to keep me from building this thing myself? Attached is a picture of my hand drawn plans. I know it's HUGE, but I want it to fit in the existing fireplace, yet still draw properly w/ the doors open to give the "open fireplace" feel.
Does the 1:10 ratio still apply for the stove pipe needed? I'll be limited to 8" in order to fit around the existing smoke shelf. I can scale down the stove if needed to accommodate the 8" pipe. It will be set off the concrete floor w/ casters or blocks, then lined w/ fire bricks. I'm not worried about being up to residential code since it will be in a rock/concrete cabin that just gets used a few weekends each year. Thoughts? Am I crazy? Will it work?

I've been searching craigslist, there's just not much that fits my needs out there. I certainly want it to be safe, All I meant is that it would seem fairly simple to reproduce a steel wood burning stove with thick steel and the proper ventailation. What more are there to stoves that I'm missing? Thanks for the replies!

Warping is certainly an issue, and frankly I guess there is a reason not many people weld up their own stoves. Thanks for the replies, all good advice.

I would stay w/ the open fireplace, but it is so wide open, it sucks what little heat is in the room and sends it straight up the chimney. An insulated roof would help, and maybe a fresh air source, but there's still no way to keep it from burning through a rick of wood in three nights! Would plumbing the chimney with pipe and capping it slow down the airflow any? Or without a stove, is it a waste of time?