I like statement modifiers at the end for simple things like an early return, or throwing an exception. To handle longer lines I use indention:

die 'Detailed error messages are important, especially when this error
+ happens'
    if $oops;
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But with the long exception you showed I might do:

Exception::Of::Doom->throw( 
    error => 'Detailed error messages are important, especially when t
+his error happens', 
) if $oops;
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I often hear that switching the order is difficult and that it is a good reason not to use the trailing conditional. In practice, I haven't found that switching the conditional around to be that onerous. A good text editor makes it easy. If switching was so hard you would see more of this:

do {
    turn_green();
    throw_up();
    die "Ach, food poisoning";
) if $ptomaine;
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