Any candidate needs to find a way to appeal to people from the other party without abandoning their own party. These voters can make a difference, but you still need to get a substantial number of your own voters. So abandoning your positions to pander to the other party won't work. And that doesn't seem to be the strategy used in single party elections in districts like CA-8, CA-30, and CA-31 in 2012.
Democrats aren't inconsequential in CA-25. In 2012, the Democrat got 45% of the vote. Even with lower Democratic mid-term turnout and a 20% blank ballot, you're still talking 33-35% of voters being Democratic. If one candidate gets 80% of those voters, he only needs to get 35% of the remaining vote. That's fairly easy for a Republican who has an established base.
Since neither Tony Strickland nor Steve Knight can afford to get trounced with Democrats, they can't ignore them. Democrats know this and have invited the candidates to a forum on August 1. I'm sure neither wants to be there but if one goes the other can't afford to not go. I imagine this forum will be beating up Republicans with slanted questions and Barack Obama style straw men.
"Trickle down economics benefits the rich and hurts everyone else. Will you be supporting it?"
"Do you plan to work with or against the President?"
Obviously neither candidate can abandon their positions and start supporting Democratic positions. That wasn't necessary in any 2012 election. But how do you answer these questions in a way that appeals to Democrats but doesn't turn off your core voters?