Define full installation please?
I see Frugal as a Full installation. If you're talking about scatter mode install, I don't believe that is supported, certainly scatter mode install is discouraged.
USB-HDD & USB-ZIP is relative to BIOS compatibility (These modes use whole disk only). I'm thinking PC's with a BIOS which needs USB-HDD and USB-ZIP support are almost extinct
That said, I think maybe there is some confusion over Full install??