I'm trying to locate my ELT mount in the Sonex I'm building. One place that comes to mind is on the shoulder harness bracket, about 4' behind the cockpit . Advantage is it may need no extra bracing and it's out of the way. Bad thing is it may be too far out of the way. If I need to activate it manually in case the remote switch fails, then this could be a deal breaker. I'm small enough to crawl back on top of the cross braces for annual checks, but I'd not like to do that with a hemo-pneumo post crash. I see most people have mounted them where they are more easily accessible.