Hello I have diggers too I have found a solution too.
I built a sand box for my dogs I have 4 Vizslas 9years, 6 years, 5 years and 6 months. 2 german short hairs and a black lab so yes they dig.
I have two homes and both back yards have dog sand boxes. I built them myself one is concrete and one is like a sand trap on golf course.
To build sand box I dug a hole cleaned out dirt and plants. DO NOT USE CHEMICALS to get rid of grass, plants, weeds etc. When stuff is dug out of hole put ground cloth as barrier. Fill in sand box with childrens play sand and sand box is done. Simple solution. but u have to buy childrens play sand and do the work.
To get Vizsla to play in sand box burry training treats and when found reward pup with vocal praise. If digging in other areas and u see it walk dog to their sand box after saying whatever u use when unacceptable is corrected. Hope this helps