Hi,
Other people help me with Viper stuff, I can offer some help to you on this one. I imported a Viper myself last fall.
(1) Get yourself a customs broker. This is far and away the most important. The $150-$300 is the best money you will spend to get rid of the hassles. Get a customs broker that actually works at that border crossing with an office on-site.
(2) Import on a weekday during business hours. If you go with a shipping company, they may not realize this. The US side has an export team for vehicles and they only work certain hours, such as not at all on Sunday. If you try to export on a day they aren't there, apparently the US side can impound it in some crappy lot (no guarantee of safety to the vehicle) until the day that the team is in.
(3) Choose your border crossing wisely. Not every small crossing has vehicle export guys working, nor even many customs brokers to help you. Would **** if the border guards sent you to another crossing.
(4) I believe many states are set up that if you pick up the purchased car on/in a trailer, you don't have to pay that state's tax (ie California), but if you drove the Viper away you would have to pay the state tax. Some states (Texas?) don't have a sales tax, so more of a moot point.
(5) I recommend bringing some documentation that shows in plain English that a Viper is made in the USA (thus exempt from extra duty at border, as per NAFTA rules). I also would recommend some documentation that shows fair market value of that exact vehicle, or proof of arms-lengths market valuation like the fact that it was bought on a competitive auction.
(6) If you would have been able to leave the car it in the US for 16 months in storage, it would be 15 years old you wouldn't have to do any hassle of modifications for headlights, child restraints, etc since it would turn 15 years old and be exempt from needing any mods through RIV program.
(7) My understanding of the earlier daytime running lights (in the earlier generation anyways) is that it is just a plugin, like a fuse or something. Everything else is already on the car and you just buy this DRL flasher and insert it in the required place, and problem solved.
Best wishes and good luck!