So I am wondering:
1. Do I have to use an importer to bring the truck/camper in if it is 25 years or older? If no, am I opening myself up to enormous hassles?
Working with the shipping company and customs was a hassle, but not the ultimate hassle. If you use one of the small number of RoRo shippers--I used Walenius Wilhelmsen Logistics--they are used to all of the procedures and will likely have your paperwork in order. And if everything is complete and accurate at the port, Customs will be doable, too. But it's all a big, strange world down at the docks, and it might be worth some money to know someone experienced was handling the importation for you.
2. Is the Ro-Ro the process I should be looking at? The truck wont fit in a container, so the seller would be getting the truck to the port and onto the ship for transport. I would then be looking to get the truck transported to Colorado (how I am not sure yet - enter recommendations here.)
For something that can't be containerized, shipping on a the enclosed RoRo ships is a good deal more secure and quite a bit faster than having it as deck cargo on a general-purpose freighter. (My Mog came over with about a zillion Volkswagens.) Have the seller lock the cabin with everything valuable shut in it, and have the key to the cabin door mailed to you, leaving only the ignition key available to the crew so they can get the truck on and off the ship.
I wouldn't proceed without a good scheme for getting the Mog to Colorado. A pretty slow, noisy and, most of all, new-to-you Mog is not a very good choice for a 2,000 mile interstate cruise to get you home. (I had more than enough adventure getting from Tacoma to Portland.) All will be well once you're used to the truck and have an on-board selection of equipment and tools to cover contingencies, but if you're going to set out unequipped from the Baltimore docks and head west, expect an adventure (and bring a music player and earbuds). On the other hand, if you ship it, you will almost certainly need a lowboy transport, whcih will seriously inflate the cost. Get the weight and exact dimensions and make a few calls to get a ballpark idea of the shipping.
3. Apart from the large amount of inevitable paperwork and the cleaning of the vehicle, what other known areas of concern should I be looking at?
The scariest part is wiring the funds to a foreign country. Make sure your seller's reputation is impeccable and that he/she/it is used to the paperwork for the shipping at the European end. Be very certain of the title being correct in every aspect. You might want to check out the CBP importation information here:
https://help.cbp.gov/app/answers/de...ments-for-importing-a-vehicle-/-vehicle-parts
and take a look at the all-important Form 7501 you covet to make sure you can provide all of information and documentation they'll ask for.
======
FWIW, I've found your questions and approach to this possible importation to be very good and your approach quite realistic. Getting the truck in from Germany, through Customs, and through the state DMV is an adventure, kind of like, and about as stressful as, doing a difficult trail. Your circumstances are very similar to mine when I imported Camper Mog . . . no vehicle like it in North America and it was 25 years old and what I wanted. It was pretty much a voyage through the unknown, but once I got the plates on it, it was a great feeling of accomplishment.
Incidentally, thinking about a European Mog now seems pretty shrewd given the drop of the Euro versus the dollar. It's a great time to buy a European Market truck given the Euro is near an 11-year low today ($1.12), and the savings versus a dollar-denominated truck will help offset the importation expenses if you decide to go that route.