Too much effort!
Wow. Putting nuts on each bolt seems like it'd take a lot of extra time and effort. Personally, I've never had a screw back out into the tube, but I'm sure it happens. When I first started making studded snow tires for my (and my friends') bikes, I used to use pan head sheet metal screws (~3/8-inch long) and just use a drill/screw gun to screw them in from the inside. I'd put a layer or two of duct tape over the heads and I was off. Since then I've revised my methods. Once I come up with a pattern will fit an even number of times around the tire (I don't put a stud in every knobby), I press an awl (like a screwdriver with a point instead) through each knobby. Then I use 1/4--3/8-inch pan head sheet metal screws. Once they're all in, I clip off any excess screw protruding from the tire--trim them flush. In trimming them I've found that they are less likely to tear the tire, they don't just fold over, and it cuts down a **** load of rolling resistance. I also don't bother taping the heads--instead I run a thick DH tube. Anyway, I'm sure that there are a million different ways that this could be done; this one just works for me.
Primus