I’m not quite sure if that would work with this method of pxebooting, as the file system that it is using is a squashfs file system.
The main complication that I think you’d find is trying to get the storage to happen over a network (I’m assuming that you’re still trying to eliminate having storage attached to the client as that is one of the main perks of this method, at least for us). Based on my quick reading of adding persistence to a liveCD, it expects some form of locally attached storage to save on, and I don’t think it would be a simple matter to change the squashfs that the livecd is currently using. If you had some form of SAN that the computer could access, then your method might work…
Personally I’d be fairly hesitant about doing this anyway, as I’m not sure how the persistent storage would work with the same image being deployed to multiple computers. I would assume that there would have to be some extra work that would need to be done to ensure that multiple machines didn’t attempt to tamper with the same data, though I could easily be wrong. It would definitely be interesting trying to implement that, but unfortunately I don’t have the means to accomplish that where I currently am or the permission to.
Depending on how many different images you needed to deploy, you could potentially make a different image for each custom deployment, but that would most likely be impractical. We didn’t have to worry about that issue, as we mainly wanted these clients to serve as terminals that users could use to RDP into various machines as needed, so there didn’t need to be any different configuration between various clients.