Answer: No, I don't think you're nuts.... but you are inviting a huge project which has the potential to become very expensive. Full grown trees are difficult to find and difficult to plant without the right heavy equipment; removing the redwoods, including their root systems, might require a great deal of excavation. Why not visit the following website and select a landscape professional, then give several a call and have them come out and give you an estimate? You may very well decide to either leave the redwoods, or to start with a much smaller tree...
Best wishes with your project!
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