I had absolutely no problems crossing the border with my F-150 truck and trailer. In fact, the US border guys even let my mother-in-law stay in the truck while my wife and I went into the CBP building IOT get all the paperwork stamped (normally no one is allowed to stay in the vehicles; the border guys tend to give us a break as military pers). I had my Kia Forte shipped here. That was not fun as the Canadian shipper damaged the **** out of my car. A strap on the car above mine came loose and pelted my car down the road. Plus, somehow the bug deflector was 3/4 ripped off and the bottom front of the car was badly scraped. The shipping company had to pay for the repairs and a car rental, but that was a serious pain in the *** dealing with them.
I'm not planning on using a car shipper upon my return APS 16. I'm going to see if IRP will pay for a Uhaul car trailer rental as I plan on pulling the car back with my F-150.
I still have Cdn plates and registration. My US insurance kicks in on 1 July. I told them that I have Cdn plates and they didn't seem to care. Insurance is more expensive down here, especially if you change your plates, registration, insurance, etc. over right away as you'll have zero American credit history. After one year, the cost will go down significantly as you build up US credit history (I now constantly get mail offering me credit cards, insurance, etc).
For your vehicles, get letters of conformance from your manufacturers. That will help when crossing the border.
I looked into changing registration to down here, but be prepared for BS. Most States have the need for "titles", whereas we usually down have these for provinces. I have loans for my two vehicles and thus "liens" on them. The States throw in the added "fun" of titles and not all of them do this electronically (you'll be surprised how behind the US is for a lot of things that we take for granted in Canada, e.g. chip cards for debit/credit cards, privacy in banks, etc). One of my finance companies (hint: it's a bank with the word "Scotia" in it,
) has outright refused to send a letter to the Department of Motor Vehicles as they won't "release their interest in the vehicle". Ya, right, I've been paying it off for 4 years now and have one year left and they're being pricks to me. Grrr...
On a different note, I highly recommend becoming a TD Canada Trust customer if you are not. Also, get a credit line with them. When coming down here, open an account with TD Bank (this is what they are called down here), but be warned that they are NOT the same company. TD Canada Trust does own them though and this makes it really easy (and free) to transfer money from your Canadian bank accounts to your US bank account. Open a US dollar account at TD Canada Trust as this is necessary to transfer US dollars from your Cdn bank account to your US bank account. Plus, when applying for a US credit card, tell TD Bank to use your Cdn credit history. If you go with another US bank, they will give you a silly credit card with something like a $500 credit limit, whereas with TD Bank I was able to get a very decent credit limit (>$15,000). Of course, this will be dependent on your Cdn credit history. I use this card to pay everything as I get pts (that I've used for airplane tickets), pay it off immediately, and have paid $0 in interest so far. Google "TD Cross Border Banking" and read up.
Another thing, due to the lack of US credit history at the beginning of your posting, you may have problems getting a TV or cell phone provider. DISH networks outright refused to give me equipment, so I went with Comcast Cable (who you go with will depend on the area you live in). For the cell phone, I went with Verizon, but tell the people at the store to tell their call centre (trust me, this will happen) to use your Cdn credit history. My wife and I had to go into the Verizon store three times prior to the Call Centre person finally saying that they could use our Cdn credit. Literally three minutes later, we were signed up.
The key is, "patience is a virtue".....
Hope this info helps...