hi, can you not use a helper address but send traffic to the broadcast address of the destination network? You'll need "ip directed-broadcast" on the inbound interface of the destination router. Failing that a "multicast helper-map" is designed to translate broadcast to multicast the broadcast again. This could also be configured to get your required solution but would require multicast enabled (so may be overly complex).
source of broadcast
int fas0/0
ip helper-address 2.2.2.255
exit
ip forward-protocol udp
ip directed-broadcast