Metasploit Over Wan

so i was thinkig to try metasploit over wan and i have few question to be answered. i have victim lan ip and i have access to they router so i was thinking to enabe port forwarding on they router and try to send payload through router(is it good idea). and i have problem with my modem (i dont use router)he dosent support port forwardin so is there any solution for that problem.

thanx