HDTV2DVD, how to fill the entire disc?

[lumis]

After a multitude of problems editing out the commercials from my transport streams, I've finally come to the part where I feed HDTV2DVD one large transport stream. The only problem now is that HDTV2DVD isn't filling up the entire disc, I've tried clicking "Auto-Fit" and even checking the "DL" box.

I removed the 2 other video/audio streams that I didn't want from the transport stream with VideoReDo Plus, I then cut out the segments of video I wanted with Womble Mpeg-VCR and then I merged those segments together.

The transport stream I have now is:
1 hour 9 minutes and 15 seconds
ac3 audio @ 384kbps
1280x720

HDTV2dvd is outputting to 4.02GB

I wouldn't expect it to fill up a dual layer disc, but I would expect it to fill up a single layer disc.

Is there anyway to fill up the disc, or is the size of the output set by the length of the video input?

[ChrissyBoy]

It is the duration of the movie which is important here. About 1hour 20 mins would fill a disk...