Sorry for waking up an old thread. I believe that the OP has had his problem solved already. However, I would like to bring the future visitors' attention to another WinPE build which is not very popular.
Also, I feel that this is probably the best answer to the original query:-
I have been trying with frustratingly little success to create a custom WinPE build to act as a lightweight OS for an arcade cabinet.
-ichimitch
AOMEI PE Build Environment (see attached screenshot) is a very light WinPE build which contains the basic Windows PE with simple explorer shell and networking capabilities integrated out of the box. Although the attached screenshot is of it running in a VM, it does work properly with actual hardware too.
Custom WinPE build Please note that I am
not referring to AOMEI PE builder - The PE builder software uses the PE building environment provided above and adds some recovery tools to it to create a recovery-oriented build. This is undesired, hence we directly use the base environment from the above link.
Download the archive
-> Extract the boot.wim
-> Either use it as a RAMdisk or
apply the image and use it like an OS 
Btw, do you have a solution for the (free and forced, but usually undesired) reboot after running Win PE for 72 hours?
-Ath
Check
this out. But I've never tried it myself because my use case never exceeds 72 hours.
