Our excavator/installer balked at a similar request "for safety reasons." I believe he said two feet was the minimum for the perimeter ledge, and on one side, he insisted on a gradual slope in to the deeper water "making it easier to for someone to get out of the deep part if they're panicking." We finally decided to do 4 feet all the way around, and dig out the center (with his "required" slope on the deck side). We have a Doughboy - I think they have diagrams on their site showing how they usually excavate the deep ends.
Are you looking to DIY this, or hiring someone? We got the "2nd choice" install team, and our depth is pretty inconsistent everywhere.

When we eventually replace our liner, we're going to ask for the "1st choice" team and reconfigure it to have a bigger deep area now that our daughter and her friends are taller and doing more underwater things instead of doing gymnastics in the shallow parts.