I think you had a good idea. I use leaf springs to make digging tools as well very sturdy, I shape and refine them in my forge. I used to sell them but have not had any offers as of late. I make digging tools along with other tools / knives for people out of old lawn mower blades and other scrap they bring me sometimes for free if I like the idea.
But I understand after buying 4-5 different digging tools I began making them got tired of having to stop mid hunt because the handle breaks off or blade bends.
Sometimes a strange Necessity brings out some rough looking if not down right ridiculous inventions that work amazingly.
Below is one of the ugliest diggers I have ever made and a re-bar knife for someone to pick up this week. The Digger is made out of a old lawn mower blade but I still use it because it works
has a hook on it to cut through roots and it moves hard pack easy if needed, there are so many rocks in the soil where I live in Pa. I would say it is unbreakable since I am around 260lb and I have had to kick it to remove some giant rocks from out of the ground to get to my finds, if it supports me jumping on it I think it is up for any other task
All I say is, whatever works for you to make your hunting more enjoyable. HH