I am unsure of where the exact route goes but if you get a chance to visit the German islands of Fohr, Sylt and Amrum it would be fun. There is a ferry to Fohr & Amrum from Dagebull and a train to Sylt goes from a little furter up the coast. It is only a short crossing.
I prefer the island of Fohr out of the three.
http://www.foehr.de/
It is flat (they all are) green & picturesque, with some nice little thatched villaged, windmills etc. Wyk is the main town/harbour on the island and it has a very nice promenade, small and friendly/character.
The beaches at Goting (FKK), Suderende are lovely...flat and sandy. The weather there is variable being a north sea island, but I have spent days on those beaches and to be honest it was better than being in the caribean. This is the island for the German 'family' tourist.
Sylt is not as picturesque although still very nice.
http://gogermany.about.com/od/greatdestinations/p/sylt.htm
It is basically one huge sand dune. The beaches on the western side are world class...miles and miles of white sand backed by dunes. The beaches are all FKK beaches...so that is either a plus or not depending on your view. The beach saunas are worth a visit, especially after a days ride i would say. This island tends to be frequented by the wealthier German holiday maker...it isnt cheap.
Amrun is a very quiet & relaxing place.
http://www.amrum.de/cms/website.php
Not much at all going on. It is another large sand dune really and is my least favourite of the three islands. It is perhaps the 'couples' island...you know, lot's of peace, quiet, FKK beaches etc. It isnt as green as Fohr, but again has some stunning beaches.
You could do these islands as a sort of 'mini tour' off of the main tour. I suggest you spend one day on each, maybe two or three on Fohr/sylt...but Amrum...well I spent just one day there and I wanted to go back to Fohr!..however it was raining and cold when I went there, in the sunshine this place would be ideal for getting away from everything. The ferry acts like a bus service between the islands...roll on roll off.
I have been to Fohr 6 times, each time for two weeks. It is a special place for our family...I know it pretty well so if you need any more info let me know.
Basically if you are heading up to Esbjerg you will be passing Dagebull anyway...the islands are just a left turn off the main route.
As with all islands, weather is key. When the sun shines these islands are superb. But if you get a storm, they can be pretty bleak.
One thing though. These islands are popular amoungst German holiday makers (and for good reason). You won't find many other nationalities there and certainly no of the 'yob' culture etc. The accomodation tends to get heavily booked up in advance, especially the larger family houses for rent, and they are not cheap either. There are accomodation agencies in the main towns and one good one in WYK.
I am unsure about campsites, as I never camped there.