I have made a grave mistake... shot S JPG instead of RAW!

I had an outdoor shoot a few days ago, so I grabbed an SD card and threw it in the SD slot of my 5Dm3 and took off.

I have been shooting in the studio all winter, and when I do, I use a CF card for RAW and an Eye-fi card in the SD slot so I can tether to an iPad and the clients and look as we go. I keep the eye-fi card set to the largest S JPG for faster transfer to the iPad.

Long story short, I had my head up my hiney and it did not even occur to me that I was shooting the entire shoot in S JPG until tonight when I was downloading the files to start editing. I am horrified. The images look decent on my monitor at 100% before processing, but the files are only 1 to 2 MB, and the dimensions are around 1920x2280 at 72 ppi. Will these even be printable?

You should be able to print them, but the quality will depend on the size, viewing distance, & subject matter, won't it? Run some tests.

THIS LINK is for onOne's Perfect Resize 9(AKA Genuine Fractals). It is usually used for making poster-sized prints from normal resolution files, but I have had some good luck using it to increase web-sized files to normal-sized files. It's worth a try and you can try it for 30 days free.

Those should print as 5x7 with no issues, but anything larger has to be enlarged.

Have the camera settings displayed at all times so you can see if say you've slipped more EC in by accident, or the file settings are wrong.
But you will adapt your work flow so you never make the mistake again.