With most routers you never need to update/write to the uboot-env area. It is usually marked read-only in DTS. (Dual firmware systems are the exception)
From that perspective, keeping that as one partition might also work.
4000 bytes is not a typical erase block size, so having that early part as writable partition might be problematic. Are you sure that there is not a copy of that at 40000 like you wrote two weeks ago in Porting to DIR 815 B1 - #8 by dgen
Ps. A 32 MB ram device will pretty likely not be accepted to the main OpenWrt. Too small for the current code.