Here is something I threw together that works and suits your needs from what I can tell.
What it does is converts each date to a number. From there I store the max start date and min end Date in fields outside of the table. I left all of those numbers visible in case you need to change anything. All you would need to do is copy over those equations and replace them with your fields.
I really hope this helps!! Let me know if you have any questions.
Edit: Theres a bunch of rules and conditions on data validation so make sure you look for all of those.