Looking at the dhcp_server.py for reference, I see the *-parameters were considered to be deprecated:

# HACKS AND TRICKS
#
# check for 'raw' ISC DHCP parameters configured by users
# actually this is a bad idea in general to pass raw parameters
# from any user
#
# deprecate this and issue a warning like we do for DNS forwarding?
if conf.exists('shared-network-parameters'):
    config['network_parameters'] = conf.return_values('shared-network-parameters')

Now I'm not sure whether this would be a welcome addition to dhcpv6 server.
My particular use-case that I considered this for is assigning per-static-mapping DNS server config (manually migrating clients enrolled into a IPA domain means I have to have some clients pointed to old DNS servers and some to new, currently I get by with setting static v6 addresses on the clients)