Are you really sure, Mike, that your question is about proving (or hoping to prove) God's lack of deceitfulness? Perhaps the question you're unable to ask yourself involves human deceitfulness -- specifically, the ability of the human brain to become so addicted to status and so addicted to "the right to be right" that there's nothing to be said and nothing to be done to overcome the brain's ability to choose denial over faith?
One of the things I find so interesting about the Gospel of Mark is the almost complete absence of any interest in the Book of Genesis, although Genesis was certainly known to Mark's author. It's referred only once in Mark 10:5-9, and even that short passage is mediated through the words of Moses. The Markan passage teaches us that God is more interested in committed, loyal, heart-based relationships than in legal oaths that bind us to each other without heart, fidelity, or faith.
If, as you believe, the world is only a few thousand years old, then Jesus himself was even "closer" to the date of Earth's origin than we are, and presumably closer to the "true" timeline you think is hidden out there somewhere. Yet, according to Mark, Jesus isn't remotely interested in either the timeline of Earth's creation or the hidden facts that might support it. Jesus clearly trusted God enough to let go of any such worries.
As we can be quite certain that Jesus himself didn't think it was a good idea to challenge God's trustworthiness (which is, in fact, what you're doing in this thread, whether you accept it or not, Mike), perhaps it's okay for us to follow Jesus' lead and focus on how to heal our relationships with God, each other, and ourselves in the time given to us on Planet Earth. That's a huge challenge for any of us to do well.
It's also quite extraordinary, from a neuroscientific perspective, what happens to the brain's wiring when we start from the bottom-up with the questions and solutions Jesus presented to us instead of worrying first about the top-down questions you're asking on this thread.
Jesus (brilliant physician, healer, mystic, and humble person of faith that he was) understood and taught that if you want to be able to know God during your humble human lifetime, there are many big questions you can't answer and will never be able to answer even if you have all the knowledge of all the human beings who have ever lived. One of these big questions involves the creation of the universe. Although we, as humans, are naturally curious about this creation (because we intuit a powerful backstory that tells us more about the amazing and wondrous Mother Father God who love us), it's simply pure hubris for human beings to believe they have the right to know all the intricacies of this process, let alone the "right to be right" about our assumptions and conclusions about said process.
One thing Jesus was very clear about in his teachings was the need for us to have a thinking faith based on a blend of heart, mind, soul, and courage rather than a blind faith based only on the mind and the law.
It takes a lot of courage to let go of the idea that the human brain -- any human brain, including the brains that wrote down the words we find today in the Bible -- can or should be able to know everything in God's book of historical facts. We can know some things -- indeed, Jesus taught us to continually ask hard questions and let go of old answers when we realize that the old answers are getting in the way of our ability to build our relationships with God, each other, and ourselves -- but we can't know everything.
If you can manage, in your human lifetime, to fully understand and live by all the basic principles espoused in Jesus' parables and Kingdom parables (which in no way reject or contradict the wonders of pure science), then, my friend, you will have lived a very full and meaningful life blessed with love, forgiveness, humbleness, joy, hope, and the peace that comes from knowing you are loved completely by God. No matter when God chose to create this poetic planet we live on.
Edited for points of grammar.