I am using both the plugins "Random Posts" and "Simple Tags". Both are supposed to write their output to the feed, which is working without problems.
The only thing that I'd like to have changed is the order: at the moment, the random posts come first, then the tags - I want it the other way around.
In "Simple Tags", add_filter is used on the_content with priority "999993". I tried to set the random posts priority to "999999", which should put it AFTER the tag output, but that didn't work.