it's not a matter of them getting you a ticket or impounded, it's the fact that they aren't designed to spin @ 60mph, the g forces on a tire that size, at 60 mph are massive, this is why tires, rims, and even valve stems have a speed rating on them (for instance, z rated tires) the reason is under heavy g forces, things tend to disintegrate, and if that bead lock comes off at 60mph, is it A) a massive projectile B) going to make your tire fail massively C) going to make YOU 100% at fault for the accident that just happened and you civilly and criminally responsible for all damages and/or injuries/death or D) all of the above?
honestly dude, for what it's worth, and the safety on something like that, don't mess around, just do it the legal way... the non DOT bead locks are fine for massive torque off roading, because you aren't spinning them 1000000 times per second, you are putting lots of torque on them and there is accelerating g's but no centrifugal g's the most you are going to get accelerating wise is maybe 3-4g's MAX
i'll put tires that are legally too big on a truck, i'll put more lights on than are allowed, i'll make my exhaust sound like what ever the hell i want, but this isn't the same deal...
i worked this out long ago, but on a standard size car tire, the outside of the tire spinning at approx 30km/h i think was putting out 8 g's, so at 90km/h (about 55mph) you are looking at about 22 g's if my memory serves me correctly
to put THAT into perspective, not only is that equivelant to putting 22x the pull of gravity on something, (22g's) but because it's centrifugal, these 22g's are all working to pull each part outwards, away from the hub as hard as possible...
for the price difference, just get ones that are DOT approved, much safer, and shouldn't be much different in price, the staunt ones are DOT approved and work on ANY rim, much safer, and you aren't liable if anything DOES happen