Clean Zipper - about 1+40 and 800 nautical is a good guess. Winds,
ATC, and pilot technique can change that but not by much. That's
normal flying - a max endurance profile would give you a little more
time aloft but it'd be a boring flight stooging along at max L/D,
especially the idle glide descending to your destination. ATC would
probably screw that up letting airliners go in front of you. BTW this
is observing USAF VFR min fuel - 20 minutes (800#)at destination.
Walt BJ