There's not only airbag compliance but crumple zones to consider. Still, if you're handy - and can weld really good (like ScottyBobcat can - man he does a neat weld) then there's no reason why you can't try it.
Insurance will be an issue. Most bullbars have to have compliance certificates (not normally handed to the owner, but a sticker placed on the bullbar indicates that that model bullbar had been certified). The certification process used to involve smashing cars with the bars mounted on them, but I did hear that at least one government was allowing computer simulations and certifying off those. Uncertified = unroadworthy and that's the crux of the issue for insurers.
However - and here's the next escape clause - if your bar LOOKS good, an assessor looking at your vehicle might overlook the lack of certification and you're clear.
It's a risk, but perhaps you could see what it takes for the new certification process (including cost)?