I'm late to the party, but used to work for a collections attorney who specialized in SMB who were close to or are defunct. The biggest mistake anyone ever made (when setting up an LLC) was to mix personal and business funds. It made it trivially easy to go to the court and "pierce the corporate veil" as you so aptly put it.

The way you wan to do it is set up an LLC but then "loan" the business money and act both as it's owner but also it's creditor. This separates you in the eyes of the court.