Like I said registered importer. if it is possible to legally bring one in, they can do it. I have spoken to several at length and they can get me a newish Nissan Patrol legally. It has been awhile and I don't recall all the details but I know the basics are that the vehicle is brought up to US standards, set forth by the EPA & DOT. Glass, headlights, turn signals, air bags, side impact and much more all come into play and have to be changed out to "DOT" approved. Sometimes this can not even be done since the parts are not made or can't be easily made for the said non-US vehicle with the DOT stamp of approval. Emissions must also meet EPA regs.
IMHO, this all comes down to money. In the late 1980's most of the regs were implemented. Car manufacturers lobbied the government and the result is these laws. Emissions and smog laws didn't help either. The laws really are not about protecting the public they are about protecting the auto manufacturers and allowing them to control the market. It is actually pretty common in a lot of countries in the last 25yrs. Auto manufacturers have lobbied government in such and such country to keep out imports. A lot of countries have dealt with it by slapping on a high importation tax, such as 50% but otherwise anything can be brought into such and such country. Other countries like the US have taken it much farther to stop lot's of imports. Some countries you can't import anything at all no matter what.
If you look at any of the non-US Cruisers, Nissan Patrols and a few others since the late 90's they have exceeded US regs for safety. Emissions are also very good for most models, both gas and diesel. Are they up to par for US emissions regs? I can't say for sure and it varies state to state. Bottom line in my opinion is it is all about money as to why you can't have the truck you want. And that goes for getting what you want through a RI too, ie the only legal way costs tons of money.
The other option is to build it yourself or pay a shop to do it for you. Icon for example build their trucks on old FJ40 vin plates and titles. It is legal and works for them. I can build anything I want and it is not regulated by the feds, yet! I can not legally bring in newer than 25yr. old half cuts and weld them back together and sell them or even own them. I can however, use everything from that half cut besides the vin number and id plate. I can graft the half cut frame to an FJ60 or FJ80 frame. I can use the FJ60/80 frame and put everything on it and modify the 60/80 frame to my hearts content. Most states go by frame vin # and that is what the truck is titled by. However, I have had 10ish trucks get a vin inspection here and not once did the sheriff check the frame, always just the vin plate. Crossing all borders from the US to Panama, never once did they check the vin number on the frame, always the vin plate. If going the build your own route, I would suggest contacting your local DMV, tell them you are building a custom vehicle and find out what the rules are on it. The feds are not going to get involved if you build a custom truck, since what you have built has been in the system since day one anyways. In the most extreme cases DMV will issue a custom built vehicle title, which includes a vin number. On that same note, a legally imported under 25yr old vehicle often has had a new vin number issued. Since many came with a vin number that is to short and doesn't fit into our system. It just depends on what the DMV where it was first registered at required. It varies state to state and is not a federal thing when it comes to titling a truck.
Cheers