I agree with the district boundary principles you have set forth here. However, if the 42% of voters who prefer Democrats were evenly distributed throughout the state, our current system of winner-take-all voting would not allow ANY seats for Democrats.
I think we should improve the process of creating voting districts. We should also look at other solutions such as instant-runoff elections that can elect multiple people in proportion to the preferences of the people. There is a site dedicated to the principle at fairvote.org.
I've written about Instant Runoff Voting before on this blog. For a succinct and convincing explanation of how IRV can eliminate the "spoiler effect" in elections and give a greater voice to third parties, check out this short animation from the folks at FairVote.org.