Each state has its own rules regarding vehicle emission standards - so yes,it is feasible that you may get a cross look if you bring certain vehicles from one state to another - especially if you are talking about grey market import stuff of a recent vintage.
How does it work if you bought something interstate that turned out to have the wrong engine? 200Tdi into defender for example? Would it just be impossible to register?
Generally speaking if you have owned your US market vehicle in another state for a while and it has over a certain mileage you can register them in another state. California for example didn't allow the V10 diesel Touareg when it came out (actually they did for a while, then they didn't...) but, you could buy them next door in Nevada. Most dealers wouldn't sell you a new one if you only had a California address but, if you had a Nevada residence and then you put 7500 miles on the car you could then register in California.
My experience with importing Land Rovers relates to California. As it stands you can legally import a 25 year old Defender into the US so, no problem at the federal level. But, California requires all vehicles from 74 onwards to pass a regular smog check. A 25 year old Defender would not meet the smog requirements for similar vehicles of that age. Even if it were the same engine as the Defenders imported in 1993 - 1996 it would still be subject to a smog referee because there was no Rover V8 approved for that year. The test to bring the car up to scratch is mega $$$$$ and includes a sealed room to measure the evaporative emissions. At the very least you would need to change the fuel tank, filler hose, gas cap, fuel lines and add whatever smog equipment the referee deems appropriate.
The good people of Minnesota will most likely have different safety and smog standards.
You can fit a galvanized chassis after you have successfully imported the thing and got it registered in your local state. On the left coast we don't worry about rust - in the snow belt just below Canada they probably do.
Spiders in Land Rovers? Nasty fuckers is the answer to your question. Black widows and brown recluses. Your experience may vary by state.