Caloric Intake, BMR and weight loss - the "quick start"

I'm reading Matt Fitzgerald's book "Racing Weight - Quick Start Guide" and will drop in some tips as I read them. The whole concept is one I've been thinking of for years - so not too profound - and when I saw a book was written on the subject I had to read it.  It's got good stuff, could be better, but you need to compromise when you write a book.

Since Sunday I've been following my daily caloric intake and burn. I did this as follows:

1. Calculated my basal metobolic rate at bmrcalculator.org  and at 182 lbs, male, 50 years old, 6'0" and came up with a BMR of 1727 calories per day.  With a low non-exercise activity the multiplier is 1.15 for a total of 1986 calories each 24 hours. 
2. I burn 83 calories/hour.  For an average of 15 hours/week of exercise that's about 2 hours/day or 2080 calories in 22 hours.
3. on the average I burn 600 cal/hour when I workout.  That's 1200 calories/day from exercise
4. The grand total daily is 3280, which is more or less what calculated a couple years ago from Fuel Factor

I've read that it's nearly impossible to have a caloric deficit that's larger than about 20%. If I want to lost 15 lbs and get to 167-168 which I believe is my ideal middle-age racing weight (not the 150 lbs of age 25) that will mean a total caloric deficit of about 60K calories.  At a deficit of 20% or thereabouts would be 700 calories/day.  that's about 90 days, or, June 1...days before the rock 'n roll marathon.  Wish me luck