Ditto on this concept. You can't even begin to imagine the variety of things I've maneuvered into those legal envelopes. Sometimes I'll slip layers of cardboard inside as armor, or even a piece to the exterior under the shipping label as a small shield during the trip. Legal FR's are such a good underused resource. Knock on wood.

If you're out of first class packaging in a bind, invert the legal envelopes and make them normal mailers after taping them up well. Boo yaa.

If you also use the padded flat rate mailers and the item is barely sticking out, put another padded mailer on in the other direction and use the label/colored tape to camouflage the seam that shows from the slight extension.