back in the CD burning days, you could usually try to do an ‘overburn’ if it wasn’t too far over capacity. not sure if that would be a good idea for this. it has the possibility of ruining your dvd drive if you burn past the edge of the material on the disk.
Not really true, CD-R’s had a generous amount of space in the lead-out area of the disc, and that space could instead be used for data by shortening the lead-out that gets burnt. It was space already on the disc - there’s no such space to be used on DVD-R or BD-R, the specs are much tighter.