I'd put it on Bring A Trailer. It's a beauty, and that site would give it exposure to folks who might not only appreciate it but have deep enough pockets to pay what it's worth.
Keep in mind also that as of the current date this German-market truck could only be registered to a new owner in Canada, so your potential market is pretty limited compared to what it could be later on. If you can hold onto it for a couple more years until it clears the 25-year US import rule, it will open it up to a much larger pool of buyers and probably go quick.
Good luck, I would love to have it, and the work you have done on it looks to be top notch. I run a 2002 crew cab gas F-250 for a work truck, this sounds like it would do everything the Ford does on one half the fuel and be an order of magnitude better to drive. Out of curiosity, any idea of the rated payload for this?