At the moment I'm tring to cope with this solution: 

1) hts-stop.lock
2) rename download dir and mkdir of a new one with that name
3) compressed FS mounted on the new dir
4) rm hts-paused.lock

this way I let the process to continue on a realtime zipped FS.

If this will not be sufficient, with the same procedure I'll mount an external
usb HD on the download dir.

Should be nice if with the same trick of the command via filename, other than
hts-stop.lock would be added something like hts-finalize.lock to finalize the
files (removing .tmp and other works).
In fact, even if paused (probably also using -Gnnn) I can use the downloaded
files because they are not ready to be used not only for the simple .tmp
extension, but worse because have some particular signs at the beginning with
a string of NULL and some other stuff. And I don't see any image downloaded:
how can the software know where to find them? Or are appendend to html.tmp?
Whatever the case need a finalization, not only a pause.