Xvid aspect ratio display problems on Philips DVD642 with AutoGK

OK, I'm trying to backup my new set of five Six Feet Under Season 3 dvds (13 episodes, 720 x 480, (16 x 9), NTSC) onto one dvd-r using AutoGK for play on my Philips DVP642. Some other facts:

1) using 1.95 installed with ESS standalone support
2) using Xvid as the codec

My math tells me that if I specify each episode to be 336MB that I'll get everything onto one dvd. My problem is that when I run the episodes through AutoGK with the Auto resolution they often (though not always) end up displayed by my Philips DVD642 as almost 4:3 instead of 16:9. I say almost since there are black bars at the top and bottom, but they're not nearly as wide as they are on the source dvd, thus giving the appearance of substantial cropping. When played on one of my software players the AR is closer to that of the original (GSpot says 1.75:1).

On the other hand, I've found that if I specify a resolution of either 624 or 608 and then rerun AutoGK the resulting Xvid looks much closer to the original on my Philips.

My questions I guess are obvious:

1) When AutoGK yields an auto width resolution of, say, 672 (often the case with input files of this length), why is the aspect ratio "ignored" by the Philips and displayed as more like 4:3?

2) Can I adjust any hidden settings to eliminate this problem? (When I loaded the file and hit CTRL-F9 the 16x9 button was already selected.) I want to have the maximum resolution, of course, that AutoGK says it can give, but I also want to see the full width of the original video files. Thanks in advance to anyone who can help.