If it means that much to you.
Well it's true, isn't it? People think illegal and legal are synonyms for right and wrong, and it's a bad habit a lot of people have got themselves in to.
The tax system is only there should an individual "choose" to work within the legal system.
There is no law that says you have to declare any income, in fact there is no law that says you have to even pay tax.
It is just automatically taken out of your earnings, simply because you are working within their tax system.
I wouldn't even bother declaring it, it's none of their business.
You sound like a free-man on the land...