I'm sure more heat sheild = less clearance, but if it hasn't been tested, what is that safe distance? That's why NFPA 211 stops at 12", unless the owners manual states a smaller clearance. In these cases, the manufacturer as done actual testing to make sure its safe. Can't say I'd personally trust a website that says, "eh, just cut the clearance in 1/2 if you use a heat shield"
I love my woodstove, but if I were building a tiny home, I don't think its the heat source I would choose. The stoves are so small, that the burn time is a couple hours max. Hard to keep a place warm in the dead of winter, while you're off at work, so you'll need a 2nd heat source anyway. It seems romantic, off grid and all, but unless you plan on being home all winter, I don't see how it works well.