VG,
Maybe try every other or third day as maintenance which would maintain a certain base level in your system?
Or, try THC-A as your maintenance and hit it harder when the outbeaks happen. I don't have migraines but I use most of my stuff that way. I chop up the buds pretty fine and put a measured amount into a 32 oz bottle of olive oil. Then, every day at lunch I make a salad with a couple of tablespoons of the infused olive oil. Same calculated dose everyday and in a little different format than you'd get from smoking it.
I've had great success knocking down my issues, but not sure if it would work for you. Maybe sacrifice a few buds and give it a go? You'll never know unless you try if it could work for you.