Preserve original sender IP for non-HTTP traffic?

I'm load balancing syslog-ng traffic on UDP 514. I have to use SNAT automap in my environment and that is obsuring the original sender IP. syslog-ng needs that to sort the traffic by device. If this were HTTP traffic, I'd use x-forwarded-for to accomoplish this. But it's UDP 514.... Does anyone know how I can preserve the original sending IP without disabling SNAT automap?