J.B.
I am the mother of a one-year old and also have had sseveral years experience working as a waitress. At the time that I was waitressing, I was not a mother, and I got incredibly irritated when families left me a disaster to clean up. One time, this family used a specially-made plastic sheet that went under the highchair and caught all the crumbs. Once they were done, they folded it up and emptied everything in the garbage. I had nothing to clean up and loved it - in fact, I gave them their meal for free!
Now, however, as a mother myself, I seem to have forgotten all my previous irritations. Now, I leave a mess and and a slightly bigger tip. I can see the looks and the irritation on the part of the waitstaff. But I just say to myself "they aren't parents yet." No matter what you do, people without kids will think you are being rude. You may be able to minimize the mess, but until they are parents themselves, you will always cause some irritation.
My advice? Clean what you can, leave what you can't, and don't worry about it.