|I can't say I have a "better" solution as I've never used WinPE. In the past, and I admit it's been a while now since I made/deployed images, I used a network bootdisk I custom made to work in conjunction with a PXE NIC. It didn't require any special server software, just a central respository for images.|
However, this was bulky and the bootdisk had to be constantly updated with NIC drivers so at the time I looked at, and tested Symantec's Ghostcast Server
This might work for you and I unless they've changed it (again, it's been over 7 years since I used it), it didn't require a domain to function. It worked equally well in either a domain or workgroup situation.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.