Hi everyone!
Thank you very much for helping each other creating friendly space here!
I'd agree with 小狼san; Hartell might have a long sound at "Har-" and it'd be written as ハーテル
As to kanji, I think it's very interesting you gave yourself a completely new Japanese name based
on meanings of original name
As far as nicknames go, all those attempts are not wrong in anyway.
The only thing I can say is that whenever we convert words or names in foreing language(s) into Japanese,
it's usually based on sound, not meaning. Unless there's a good reason to translate it into real Japanese word,
we focus more on phonetically-converted name. You can see this in foreign names, right?
Names of foreign people will be always written in Katakana in official document if not in alphabets.
Some learners want to give themself kanji based on sounds and use it in personal occasions like letters
and emails among friends. Or, just like 小狼san does.
If you want to use the nickname, your nickname can be 鹿岡 大助 (the kanji 助 is also "helper")
whic is read as "shikaoka daisuke". This name has completely different sound from your original name, of course.
As long as you know all these info, I don't see problems.
Natsuko(奈津子),
Team JapanesePod101.com