A couple real quick points (ok, so when I finished it was a freaking codex):
Sounds like they know someone is home pretty much 24/7. Sounds like they have known for at least 3 days you own guns. They keep coming back. So, either they want your guns, or they want something else and aren't afraid that you own guns. Either way it's bad. You might have scared them off, but I don't think so. If they are aggressive enough to want inside when you are home too, they sound fairly determined. A magazine subscription guy makes what? $2-5 per subscription. Even with the high price of that company's products, do you really think it makes sense for them to come to out-of-the-way places to sell door to door? Do you seriously think he would waste that much gas to keep coming back to your place? They only target high population density areas where they can actually make some money. That company, at first glance, looks like a ponzi scheme anyway. Not what I'd call reputable. College students selling children's magazines selling $77,000 worth of materials? I call BS on that in a heartbeat. It COULD be simply a pushy (and retarded) college-type sales kid, but I wouldn't let up my guard yet.
1. Get the family out of there. Call it a vacation. Don't you have some relative they could go visit? So what if they burgle the place. At least your family isn't there when it happens. If for some reason this absolutely isn't an option, do it anyway. If possible, find a way to make it seem like a fun trip for the kids, to lessen the freak-out potential.
2. Call police and report NOW NOW NOW. YOU got his license# didn't you? You can give that to the cops. You know you can go to the DMV and pay to get the registered address, don't you? I'm not suggesting that you go to that address, but you could certainly use it to have a restraining order served if things get any weirder.
3. Tell your neighbors, or give an update if you already have told them. If something does happen (next week, next month, next year), and your loved ones have to get out of dodge, knowing who you are, and the history of the situation may mean the difference between them making a call immediately to the police and trying to figure out what's going on before they call, and in a rural situation, that means minutes lost. Hell, it may save your neighbors some grief if they get targeted instead.
4. Beef up security, both real and "imaginary". Lock the gate to your property. If no gate, then put a chain across two trees. If no chain, then tie a new rope across two trees. Add a large sign to go with it saying KEEP OUT, ESPECIALLY MAGAZINE SALESMEN, ESPECIALLY THE GUY WHO HAS BEEN SCOPING OUT OUR HOUSE TO ROB IT FOR THE LAST WEEK. THIS PROPERTY UNDER SURVEILLANCE. BEWARE OF DOG. (even if you don't have one). Put out a bowl of dog food and water dish on the front porch, half-full. Be sure and drop a few pieces of kibble out of the dish. Fake or real video camera a great idea. If you can afford it, and have time to get one locally, get one of those hunter's cameras with a motion sensor and plant it on a tree on the driveway facing towards the road (when the car comes by, it will snap a pic of the front license if any and the perp's face). Definitely get flood lights with motion sensors for the entire perimeter of the first floor (any entrances). Some of these things are expensive, some are cheap. Do what you can afford/have time for.
5. Seriously consider another firearm ASAP. If you have a range at home, use this summer daylight to familiarize your wife with those weapons when you get home from work. A fanny pack or small purse worn over the shoulder & neck could serve as a makeshift holster if necessary.
6. Seriously consider a dog. Doesn't have to be a big/dangerous breed. That's your alarm.
7. Think about your backstop from various positions in and around your house. What about down the driveway? Back door?
Those are all things you can do short term. Long term, get more guns, holsters, and safes (for stowing weapons around the house out of little hands), and TRAIN THE WIFE how to use them. Make a habit of giving NO, NONE, NADA, ZERO information to the perps, or better yet, lie to them in convincing ways, or even push back as much as you can. "where do you work?" "County sheriff's dispatch". "You work a lot?" "that's kind of nosy. I don't like your questions. Stay off of my land." Not criticizing, just pointing out a habit you might want to cultivate.