I always get murdered after the first siege. This way of building doesn't provide much protection. But it's nice to know somebody else tried this too 
If you're going to try this, I strongly advise a military-oriented setup.
Bring 8 Iron Ore, 30 Flux, and 38 coke in some form; probably coal or just wood or even an axe. That'll net you 30 Steel, which will make 6 breastplates and 12 shields. Make 6 of your dwarves level 10 in armor and shield and have them do nothing but train after the first minimal habitation is built. The one remaining dwarf ought to be skilled in weapon- and armor-craft. The shield skill levels up for both attacking and defending; being still allows them to hit harder (iron would serve as well). Bring enough food so that your people don't starve. You won't get anything much really done until migrants show up.
That's about it. As your military reaches legendary, split them up and have them teach apprentices, gradually growing the army.