Clam makes a bag for that setup.
Based on reviews it is huge:
“Cover is quite large for the Clam plates. I assume it is made for many different augers. It does what it is intended to do and is well constructed.”
“This bag is massive. I use the clam drill adaptor plate with a 20v dewalt hammer drill and the bag is very loose. It’s made very well and does it’s job but could be made a bit narrower.”
“Great product for the price and good quality. The only drawback is it is over sized and moves around alot in the wind. Otherwise it’s a great product”
You could have one made, know anyone with a sewing machine.
I’m leaning on going this route if I can find a seamstress