I succeeded in compile a 3.0 pre-emptive kernel that actually functions properly with NFSv4 and rpc.idmapd.

Moreover, I’ve come to understand the compatibility issues.  The problem is that newer NFSv4 went to using nfsidmap which uses upcalls within the kernel rather than an daemon to handle mapping.

What I haven’t determined yet, is exactly at what kernel version this change was made and if it is at all possible to build a kernel with kernel nfsd support that will work with both.  That would be the easiest, else I’ll have to change all the machines over at once which would be challenging.