All of the statistical analyses sound to be fairly easy to beat.

Say you want to pretend to be another author: first build a language model of the target author, then use the model to single out sentences of high perplexity from your writing. Then, have the model "rewrite" your sentences by replacing your words with synonyms of higher n-gram probabilities according to the model. Similar things can be done to fool the character n-gram analyses, or analyses above words (e.g., parses).