Hey Casey,
The guys here are giving you great advise, as much as your post is giving them to go on. But I think you're starting out with some assumptions not based on any real experience. If you are carrying a firearm for defensive use, a overly large knife is not only not needed, but can be a PITA. If you are worried about a dog encounter, then a basic hiking stick or walking stick is all you need. As much as the owners would like to believe, pit bulls are not the indestructible animals they are made out to be. A stout length of hornbeam, ash, or oak will take care of anything short of needing a firearm. Since you have a CCW handgun on you, maybe look at some stop gap non lethal tool for use as an intermediate choice. A can of pepper spray, stick/cane, should do.
When I was young, I was gung ho enough to lug around a Randall 14 as my woods knife. Being young and impressionable, I thought it was needed. As I got older, I got real tired of lugging it and other heavy stuff around, not to mention in the 20 years I carried that silly thing, I never used it for anything that I could not have done with a much smaller knife. It got sold off, and I never missed it at all. I ended up carrying a Swedish mora and a folding saw. If I need a survival combo, spend a night out in the woods, I can do better with that combo than with some bowie type knife. I can only offer my experience that came with age as a guide, but the big bowie knife is not the way to go. Dayhiker gave the best advise here. Forget what you read in the knife magazines.
I envy you the ability to CCW a handgun. Here in the Peoples Republik Of Maryland, that is not an option, so I've had to live my life with other choices. My wife and I love the woods, and for the past 40 years I've done well without a handgun. The two times I did weather a pit bull attack on our welsh corgi, a stout hiking staff from hornbeam did well. In one case, the pit bull died from a blow to the head, the second one had to be put down because of damage to the spine from a blow across the back as it was trying to chew on our corgi. So a good stick is not to be overlooked or underestimated. You stated that there are times you can't carry a gun. I only mention the stick as you made mention of a problem with a pit bull farm. If you go someplace you can't CCW, a compact locking folder and a good stick will be perfectly legal, and will protect you very well.
The big bowie sized knife in a calf sheath may have a certain appeal, but I urge you to forgo it, and stick with the practical. Most times the big knives get outgrown and take up residence in a drawer.
Good luck.
Carl.