I suggest that you might consider making wpkg-gp do the following
1. Installing WPKG-GP (0.18b) on the current preview of Win10 (b9879) works
2. The scripts and wpkg itself seem to work okay if run manually (through
wpkgpipeclient Execute)
3. Install on boot does not work as Win10 seems to skip the GPE
The reason I suggest this is that:
Windows 10 is currently in preview, so this problem can either be a bug or a
deliberate decision (disable GPEs in preview builds).
But maybe handling GPEs on boot changed in 10 (to speed up boots possibly)
which might force a reaction.
Currently WPKG-GP does not work on boot with Win10.