I know Kansas is somewhat different than other states but did not realize you needed a passport to leave the state!
When we were in Mexico earlier this year we did NOT need a passport to get into Mexico nor back into the good old USA! But I know there is some talk of needing one sometime in the near future. We were in Mexico 3 or 4 different times. As I said.... no problems.
You do need Mexican Insurance. USA insurance is not recognized in Mexico.... and vice versa. Also if you do not own your rigs outright then you must have a notarized letter from the lien holder that you have their permission to take the rigs into Mexico.
If you do a search you will find several different threads on all these issues. Some really good and detailed information.
Good luck and have fun once you thaw out!