libpq on the server

Hi,

For various reasons (parallel structure with existing code, commonality of concepts, etc), we have C language functions
implementedthat use libpq to make a new connection to the same Postgres server.  Yes, I realize libpq is meant for
clientsand SPI for backends.  The question is, are there any technical problems with this?  Will using libpq in the
backenddo Bad Things in unexpected areas/ways? 

The environment ranges from:
Postgres 7.4.2, 7.4.3
RedHat 7.3, 9.0

Thanks,
Wayne