My squaddies and I used to take Novembers up, with 100% internal, and 300 gallons of wing drops. We'd climb up to 25-30K or so, and chase darbar that we figured for high-altitude bomber score-potatos. Some of those missions would last almost 2 hours (with all that fuel), and we'd usually come home with 4-6 kills. At that altitude, you can really expand your area of influence since you can fly at 425 mph. At those speeds you can cover a sector in 3.5 minutes.
Those were usually pretty fun missions, but we quit because of a dearth of targets. I may need to start doing those again.