OK, working this out (in public, I guess). I found two theoretical ways of doing it. First, adding the following to child-theme/functions.php:
remove_action( 'woocommerce_before_single_product_summary','woocommerce_show_product_sale_flash', 10 );
remove_action( 'woocommerce_before_single_product_summary','woocommerce_show_product_images', 20 );
add_action( 'woocommerce_after_single_product_summary','woocommerce_show_product_sale_flash', 10 );
add_action( 'woocommerce_after_single_product_summary','woocommerce_show_product_images', 20 );
Second, simply overwriting sf-woocommerce.css lines 1270 and 1278 respectively with:
.woocommerce div.product div.images {
float: right;
}
.woocommerce div.product div.summary {
float: left;
}
effectively swapping their float values. What is the preferred method?