I have a similar issue. I have a narrow heal with slightly wider than normal forefoot. I also have very flat feet. I tried on K2s, ThirtyTwo's, Burton's and Van's in the correct size with flex from 5-10. Lace types were single boa, double boa, speed-lace and traditional.
The Van's boots, with a Superfeet insole, fit my foot better than any other brand between the two shops. Heal movement is barely there when I fully press into the boot. Traditional lacing allowed me to tighten the boot where it was needed to mold to my foot. Double Boa was good, but not as nice as traditional lacing. Single boa left my foot loose and my ankle too tight.
I was down 1/2 a size with my 2012 Van's Andreas Wig boot.
This was a 5-hour odyssey between the two local shops.