I want to back up the whole install to external hard drive, wipe the PCLOS, Install the DAW Linux then install PCLOS from the USB Hard Drive. Partially because I just love the PCLOS GRUB screens so much.
First of all regardless of installing any other system PCLOS can be used to boot the PC using its Grub.
To keep that setup (or return to that setup if something interferes with it) does not require a reinstall of the OS ..... just a reinstall of Grub ..... and there is a utility on the liveCD to facilitate that .... if not on your liveCD then it can be downloaded and run while using the liveCD.
So it seems there is no reason to delete the PCLOS install and thus your main question is moot.
To generate an ISO of your complete install of PCLOS you would use the mylivecd
command, with whatever options are required for your situation.
There are lots of threads and help on the forum about this.
Having produced the ISO you can then use another small utility - PCLinuxOS-LiveUSB creator which again may be on the liveCD - to create a bootable USB flash stick or such.
There are other methods also to make use of the ISO on removable USB drives.
To begin with you need to re-asses your situation and maybe tell us exactly what you want and get suggestions about how it might be best achieved.