If you are still looking for a shipping company, check out
http://www.tgal.us/. I used them to ship my Mercedes back in June. The total was roughly $1600.00 which included ground transport from Bremerhaven to Einsiedlerhoff (where German Customs is located). I dropped it off at the port in Jacksonville myself to save about $300.00, but ground transport in the US is an option as well.
Regarding trying to use double sided tape, I tried that when I first got here with my Mercedes. The on base inspection station didn't like that too much. They were very rude about it, made comments like "are you going to trust some tape to hold your plate on when you're driving down the Autobahn?" Needless to say, they failed me, made me take it off, go back out, mount it "with screws, nuts, bolts" as they wrote on my inspection sheet, and wait back in line for an hour and a half to get reinspected. They are very strict about using double sided tape. If you are willing to give it a try though, they have a very strong vehicle trim tape at ATU for about €9,99 which I can recommend. It's very strong, and to answer the idiots question who asked me the rhetorical question I referenced to above, yes, I trust this tape more than screws. My advice is, make it look like it is bolted on, but use double sided tape. If they suspect it isn't really bolted on, they will likely fail you. I am 100% sure they were just being dicks for the sake of being dicks. To my knowledge, there is nothing wrong with double sided tape to hold the mount on per German law. I could be wrong, but that is how all the dealerships do it with no issues.