Priority Health Lightweight-Ins. help please!

I just submitted my pre-cert info to my PCP and had to get a new Height and Weight.  5'4" 231lbs which means my BMI is 39.6. I have been in a medically supervised weight loss program for 3 years, including 24 weeks of total "fasting" (eating their high protein food product).  I have regained all my weight plus5 lbs. I am in the gray area and can lose but always regain.  My ins. requires the medically supervised diet, done.  BMI 40 or more with one major co-morb.  BMI less than 40 with 2 major co-morbs. I don't have any "life-threatening" co-morbs.  I do have high cholesterol, which goes down when I lose weight.  I have urinary stress incontinence, abnormal periods, joint pain and depression with meds.  I do not want to get to the point where I become a higher surgical risk.  I want to take care of this now.  I have proven I can lose weight on a structured program, in fact in 2005 I got down to 153 lbs on the medically supervised program.  I have learned so much about myself and obesity in the program and still attend meetings. Does anyone know what I need to do to increase my chances for insurance coverage?  Do letters to your ins. co. help? Will they round my BMI up to 40?  My surgeon's scale may weigh heavier,  this would put me at BMI =40.  Over 40 BMI will make it a little easier to get approved. I understand that I am a lightweight but it is hard to know you put all this work into yourself and you regain.  I need something permanent to help me keep my structure with eating.  I am ready to work hard, forever. I need advice, Thanks, Laura