That’s a brilliant idea asking the landowners if you can put up some camera traps. It sounds as if there is some fairly decent habitat around there – fingers crossed for some interesting footage. It might even encourage the landowners to make it even more hog friendly. There is some information for farmers: https://www.hedgehogstreet.org/farmersadvice/
Great that you already have 3 hogs in your estate and some of the females may not be out of hibernation yet, so hopefully even more to come.