I use Tails on a DVD
Can I create a file hosted filesystem and store it somewhere (eg luks partition or anywhere)
Can I mount this file in the correct location and have the tails persistent feature use it?
Does anyone know how to use the tails persistence features with your persistence filesystem stored somewhere other than the default?

This should work, but is unsupported right now (see ?persistence: support DVD): install Tails on USB, boot it, setup a persistence volume on it, shutdown. Boot Tails on DVD, insert the USB stick once the
live-configstep of the boot has started but before tails-greeter appears.