Well, right of the bat E I think I need a much smaller hole in the water than you do...that helps me right there. You weigh what...200? I'm only 170. I'm sure your cross section is bigger.
Kept a good streamlined shape w/hands leading. Strong kick, slower than it was fast (yeah I know...master of clarity). I was hitting walls at about :20, taking 2 breaths and going again.
Basically I was just trying to stay relaxed. I think I could get it down to :15-:17 wall-to-wall with a 2-3 breath rest. Without a swim buddy I was hesitant to push it...the lifeguards at my pool don't exactly inspire confidence.