that is an interesting question that comes up on the NFA forums from time to time, and I don't recall what the correct answer is. usually, guys want to get an NV NFA trust (or some other NFA-friendly state) set up to have the NV trust buy the firearm in question. Since the NV trust is buying the firearm, it can be purchased in NV. The issue is, when it is time to pick up the firearm, it must still be 4473'd, and since the trust is a legal entity, a physical person has to actually fill out the 4473, on behalf of the trust. At that point, I don't recall if federal law would allow an out-of-state person to fill out the 4473 on behalf of the instate NV trust. And then, if you toss in CA law trying to require CA residents to go through CA DROS, it gets even more complicated. At that point, it may be worth seeing if the trust can be drawn up to have a NV resident as part of the trust that can purchase on behalf of the trust and have them fill out the trust.
That type of scenario is where having an attorney that knows the in and outs of trust law, and how to draw up a NFA-specific trust, to deal with those tricky situations, is important.