The best evaluation of practices which are not mentioned in the Pali Canon is, i belief, if they are conducive to the goal of reaching Nibbana.
I think the Buddha would agree with this kind of evaluation.
The Buddha himself seemed to be creative in inventing practices which were conducive to the goal. For example, the Budddha once taught a very stingy man to first give something with his right hand to his left hand. The man could hardly bare this, but he did. He practised it. He then made other steps to deal with the stinginess. As a result he came to a point where he could really enjoy givings things away to others. I do not know the sutta anymore.
It is an example of personalized instructions, personalized practice.
I belief, the Pali Canon is not written to end all such conducive creative and intelligent skillful means. It is also not meant as an absolute and complete map of all possible skilfull means.
siebe