I have a lovely yellow hosta that is about 4-5 feet in diameter and I have to dig it soon because a back hoe is coming to dig up this area. Any hints?

Ask the backhoe guy to move it. Beware of the size of the rootball!

Water slowly for 2 days before the move, when digging start about 4-6" from the leaf line. Hostas normally have a shallow root system, like Arlene said maybe the backhoe operator can do it, have the new hole all set to go and water in.

You may have to divide it into smaller pieces to make it more manageable

I would use a straight bladed shovel and divide it. They recover very quickly from that disturbance.
I can easily see 5 divisions from that mother plant and if it is a good grower, and it sounds like it is, it will only expand and fill in and be a beautiful grouping!!
Good luck.

If you want to move it all in one shot you will most likely need the backhoe. Like RJ said water well for a couple of days , have new hole pre-dug . Have the driver put it on a tarp so you can drag to new Pos. Otherwise divide into manageable sizes.

Thank you for your suggestions!

Let us know how it worked out.