Not a lot works with ground hogs besides bullets.
Predator scent repellents won't work with them,
Neither does blood baits,
They get wise to scare crows pretty quickly,
And it's virtually impossible to keep them out with a fence since they are such wonderful diggers.
What we used to do was go out in the fields about a week or two before were were going to hunt/exterminate the ground hogs and park a hay wagon with 'Scare Crows' and our shooting table on it
.And you want to place it 'Downwind' of the seasonal prevailing winds...
Had things like swinging pie pans and plates in the wind on it so they were used to seeing movement from the wagon...
They would get used to it in short order, then we would go out and remove the ground hogs, and we would replace the scare crows at the table with rifles...
(hillbilly farm kid version of a drive by!)
We often had ground hogs within 30 feet of the wagon, And it made exterminating the little buggers MUCH easer!
I would suggest a pile of pallets or a table set up with scarecrow, and remember to stay down wind if you can.
A blind set up wouldn't hurt anything either I wouldn't think...
Ground hogs often aren't out during the heat of the day, but they are VERY active mornings and late afternoons & evenings.
The only other way I know to get rid of them is poison baits.
I'm not crazy about using poisons around my potential food supply, and it's hard to find any bait food that is more appetizing than fresh, ripe produce!
I almost forgot!,
Ground hogs are pretty good to eat, especially late in the spring when you are getting the younger ones that have fattened up fresh sprigs or emerging baby crops.
Those are good just fried like chicken or baked.
If you get an older one and want to try it, flour coat/lightly bread the pieces cut up like a chicken in a skillet,
Then put them, and the skillet 'Cracklins' in the pressure cooker and make gravy out of them!
Wonderful meat that just falls off the bone and brown flour gravy to go with it!
MUCH better than any rabbit or squirrel you will ever have!
If you are going to try and eat him, DON'T USE A CANNON!
.22 WMR is about as big as you want to go if you intend to consume the little rodent.
'Varmint' bullets tend to make a mess and fragment, so even if you pop him in the head, you just never know where those bullet fragments are going to show up!
(The voice of experience here... Some of us had to learn the hard way
If you aren't worried about fragments in the meat, or just turning him into a gory mess, then by all means, use a .22-250 or .223 or something like that...
The do make pretty good fertilizer, but the hide take FOREVER to decompose under ground, and even buried a foot deep, they will draw in predators that will dig things up...