I'm so sorry for your losses, but I do have to say I agree with what's been said.
You said that you can't fence areas of your property where you can't even walk through yourself.... is your entire land like this or do you have some clear lawn/yard space? You don't have to fence in your entire property; just a small portion of it.
My dog has a very very strong hunting drive. If you let her out and are not keeping her under supervision, she will run off after all sorts of game and be gone for hours. She came back one day - shot through her thigh with a pellet gun because one of our neighbor's accidentally mistook her for a coyote.... luckily that's all that happened to her, clean wound, she was fine... LUCKY!
Now we have acreage too but due to my dog's nature and to possibly getting killed, my family and I decided to get an invisible fence. We just "fenced in" part of our lot that we use as a backyard (the rest are fields and woods) and that's the only area she's allowed to go in, unless we are with her [and she's on a leash].
I really like the invisible fence. Since it's all underground, your property can maintain that "open look" while still giving your dog boundaries.... if this idea isn't something you are up for, then I recommend getting your remaining dogs (and future dogs) a run of some sort...
Again, I am so sorry for your loses, but please consider some of the options people on this forum gave you.