Field upgradeable flash based system image?

[bob at proulx.com (Bob Proulx)]

I am trying to set up a flash based system image for a dedicated
server application.  In particular I want to use a small machine with
a compact flash based boot device.  (USB based is okay too but I have
a compact flash capable machine in my hand.)

It seems almost easy to use live-helper for this.  But I would also
like it to be a Real(TM) Debian server too.  That is I would like to
be able to upgrade it remotely with APT.  This appears to my eye to be
incompatible with the images produced by debian-live.  (True?  False?)
That is, it looks like debian-live's live-help scripts produce a
squashfs image that isn't field upgradeable.  As far as I can see I
can only upgrade by producing a new image and then swapping out the
compact flash device with a new one with that image.  (True?  False?)

Does anyone have any hints or suggestions as to the best way to
produce a flash based remove server device that is field upgradeable?

Thanks
Bob