Just having custom allocators won't automatically fix the pointer issue: remapping the file later will leave the previously "allocated" pointers pointing into o

Just having custom allocators won't automatically fix the pointer issue: remapping the file later will leave the previously "allocated" pointers pointing into old memory, which may not be where the file was remapped. The allocators and data structures would need to support using non-raw-pointer pointers types, including not even platform-pointer sized types.