According to this post:
Chad has this to say about scheduling:
Blockquote As far as scheduling your strength workouts so as not to negatively impact your endurance training, our recommendation is to separate them as much as possible but do them in the same day rather than schedule strength work on a recovery day. This allows the cell signaling the least interference, your muscles the best chance at reaping both strength and endurance benefits concurrently, and your body the opportunity to fully recover between hard workouts. And it’s prudent to recognize that the best endurance athletes will never be amongst the best strength athletes and vice versa.
Doesn’t really address your issue of adding to the weekend… Sorry I cannot help there 