I've got my work cut out for me. Origin, meaning, negation by sarcasm?

Solution 1:

Also, I am curious about the origin of this phrase, and would love to know about its first appearance.

To have (one's) work cut out for one is from 1610s; to have it prepared and prescribed, hence, to have all one can handle. Old English weorc (n), wircan, wyrcan (vb); related to Old High German wurchen, German wirken, Old Norse yrkja, Gothic waurkjan] etymonline.com

More etymology here: worldwidewords

Is there any evidence that supports the former meaning, other than being used in a sarcastic context? Or, can the former meaning be true only if used in sarcasm?

My sense is no to both of your questions.