Who says you need to keep it to 3 or fewer characters?
Many business websites only allow 3 characters.
Good luck with getting anything done with the long Chinese name.
Then also add salmon 鮭魚
But i exercised my right to do so. I wasn’t denied my right to use as many characters as I wanted.
My name in both English and Chinese script is the same, including family name, I know people who have romanised chinese names, on there ID, indidunad names are also romanised on the ID and passport (sometimes people have both chinese and romanised on the ID).
Not a thing, I known two Taiwanese with 4 characters names, one of the options for the conversion of mine was 4 but it felt a little clunky. I think the ID card has space for up to 6 printed but there is an option for hand-written ones (I have only seen this with a long Indigenous name but it think its available for Chinese also).
You can report them as discriminatory due to the naming act or whatever it was called.
Yes I need to use Chinese script on official documents, Taiwanese need to use a romanised script on UK documents, it’s the same principle.
The difference is Taiwan has an official conversion to a romanised script you can use and most people do, as the system is already set up, it’s easy but not compulsory.
Romanised to Chinese has no official standardisation so it’s up to individual interpretation, you aren’t made to change your name you’re just made to choose your Chinese representation of It. If there was an official romanised to script you would just have a name assigned then maybe the option to change it, same as Taiwanese do.
I have four in my name and have yet to encounter a website restricting to 3 characters only.
Not even that. Writing mine fully transliterated would be a grueling 11 characters.
I do value my sanity.
丁一 would be an easy name.
Tempting! 
I’m not choosing the name for my dinghy for my Chinese name.
How about 丁啊林 … i think it has a good ring to it.