I think that sounds fine as long as you follow all the other rules about different trains and don't hit delays.

The biggest concern would be getting scanned between NCR and WAS in either direction. You'll probably have to seek out the conductor. On that note, you may want to see if the price for 4 one-ways is the same as the multi-city ticket. That way if one of the early legs isn't scanned, the rest of the itinerary doesn't get screwed up or cancel out. You can then just request the missing points for that single leg later on but not ruin your day.