Hi Ping,
That is a predicament, but you are using the best insulin for this type of problem. It's pretty simple to work around though, especially since Major is regulated.
First off, I'd like you to try it first at least 2 or 3 days ahead of time to see if it works OK. Give him .5U at 9:30, then .75U at 7AM. Giving the lesser dose at +10 will maintain the overlap or shed a little longer so the next cycle can go to +14 but won't be so much that the next time you have a too-low preshot and even though the cycle after that will be a shot at +10 after a .75U dose, as long as the BG is fairly stable you should still have a shootable BG. I hope that makes sense.
If you can get some tests in between those times to see where the action goes, that would relieve your anxiety about it somewhat.
Just for safety's sake, you may want to lower dose even further for each shot, say a skinny .5U and a skinny .75U. You may want to make up syringes ahead of time for the vet, and put them in something labeled which times they are supposed to be given. There is no harm in drawing doses of Levemir ahead of time, several of us have done it.
I'm sorry your original plans fell through. If I can be of further help, you're welcome to PM me. He's doing so well, I doubt a week's worth of wonky scheduling will mess him up too badly. Can they maintain cellphone contact with you while you're away?
And for those who can't remember, I have extensive experience adjusting shot schedules with Levemir. Not only do I have a changing shift work schedule, but I am using it TID currently to overcome concurrent Prednisolone usage. A few hiccups here and there on that, but Levemir is much more flexible than it's given credit for, you simply have to understand how it's meant to work and use that to your advantage sometimes.