My exhusband was also very uptight and schedules were everything to him. After the boys were born I kind of made a game out of our scheds. If we had a trip planned it was we will leave at this time, stop for our first bathroom break at this time, etc. Well I would completly mess it up. At first it would drive him nuts then it became a stupid game with the two of us to see who could outwit the other. We still do this today even though we are divorced. It taught him flexiabilty and me to be more prompt.
My dad, father in law, and brother in law are all police officers but they are very well rounded and leave their badges at the door when they come home. I never knew the stress of my dads job growing up. It was not until I got older that I truly understood his job. As you know everyone is wired different but if you agree to hang your stress on the bushes by the back door before you walk in the house you will realize when you go to pick them up the next morning before you leave you will sometimes forget what you were so stressed about the night before. Sounds kind of strange but if you make it a daily practice it really does work.
Life is so short and if you allow your job to control you will miss out on the important things in life. Find what it is that makes him relax wether it is hunting, fishing, golf, etc. and encourage him to take an unwind day. Men are strange creatures and it seems that after a day of their favorite hobby they are much more relaxed and rejunivated. If your husband is like my ex he worries about things that he does not want you to now about such as finances, kids, being a good dad, and many other things. He never wanted me to know about these worries because he thought it made him weak. I feel it made him normal.
Anyway good luck, do not lose who you are and just keep trying to find ways to lighten him up. Just uncontrollable laughter is sometimes the best medicine.