1. I think remastering can be made easy "enough", I will post an updated version of the remastering script used here as soon as I have tested and honed it a little more, and checked it for CD version use. I made a complete remastering of 6.7.1 DVD in about 70 minutes with it (running that cloop now), but slow file copying took a lot of the time.

2. Remastering may be the simplest way to contribute to Knoppix development, and creating and posting ISOs may be useful for that purpose. Wrt bandwidth use, posting scripts may, however, be vastly more effective But I would definitely download a pure 64-bits remastering of 6.7.1 instead of creating one myself. (My 64-bits version of Knoppix is 6.4.4-based and therefore "obsolete"..) Creating further cloops might also be a solution, a cloop with ca 2GB programs would be about CD image size.

3.
I expect I might be able to pull together an 'in situ' menu-item re-
mastering from available on-line material, but it would require most
of a 16 Gb usb. That would seem to be an absurdly wasteful
use of resources IMO.
In principle of course yes - but a 16GB USB3 stick costs me about $40, so these resources can hardly be called very expensive. I also see no reason for using an USB stick for remastering if HD real estate is available, USB or otherwise. The space requirement is only for temporary use, and I use a 20 GB loopfile for full DVD remastering. With 64-bits systems and more RAM, ramdisks may also be used for this - I have 16 GB system RAM in the machine I'm posting from, more than enough for CD remastering to ramdisk.