The manually operated rear guns of the Stuka and Dauntless didn't have interrupter mechanisms, no. Powered turrets that could point at parts of their own aircraft would include some sort of mechanism, e.g. for the mid-upper turret on a Lancaster "Cut-outs are provided for the tail fins and a taboo cam tack runs around the turret to prevent damage to the wings, propellers and the tail unit" (The Lancaster Pocket Manual). The only two-seater with a such a turret that immediately springs to mind was the Boulton-Paul Defiant, it had a firing system capable of individually interrupting each of the four guns of its turret ([diagram from The Aviation Forum] (http://forum.keypublishing.com/attachment.php?attachmentid=189582&stc=1&d=1288746934)).

For simpler manually operated guns, where the firing mechanism couldn't easily be interrupted, the guns could sometimes be physically prevented from pointing at the tail; the Handley Page Hampden had flexibly mounted guns rather than turrets, and [there's a reference] (http://www.hrmtech.com/SIG/articles/hampden.pdf) to deflecting rails being added for the upper-rear mount when they switched from single to twin guns. In general, though, for aircraft like the Dauntless, Stuka, Skua etc. the gunner just had to be careful! The Pacific Aviation Museum's [page about their Dauntless] (http://www.pacificaviationmuseum.org/pearl-harbor-blog/douglas-sbd-dauntless-scout-dive-bomber) has a short section on rear gunners, including:

"One rear-seat gunner who visited Pacific Aviation Museum was asked if there was an interrupter gear to keep the rear gunner from shooting off his tail. He shook his head and said, “*&% no. You just didn’t shoot your tail off!”