Tim, after 40 years teaching high school I will be retiring in June. I haven't done any real bike touring since I was in college back in the mid-70's. I haven't even rode a bike a in too many years but started last year just for exercise. Now that I am about to have some time I am doing pretty much like you mentioned and also have the same concerns. I live on the Gulf Coast of Northwest Florida so biking is very good weather-wise but very bad with tourists. Having lived around and taught many "redneck" with their big trucks (I also drive a pickup, have for 30 years) I have found that most of them will treat you with as much respect as you have for them. I was on a very deserted back road during hunting season when a truck slowed down behind me. The combination of high-horsepower trucks, big guns, and too much alcohol is likely to lead to problems. They finally pulled slowly up next to me and the passenger reached out with a bottle of water for me, I said thanks and joked about wished it was a beer. They pulled over up the road, reached into a cooler in the back, and held out a beer when I got there. Of course I stopped and drank a cold one with them, talked for about 30 minutes, actually had a second one. One of them gave me a cell phone number in case I needed anything. There are a lot more people like that than bad stories.
Scariest thing I ever see behind me is giant motor-homes driven by people older than I am with no training at all. Lots of those on the roads around here and they sometimes will blow you out of the bike lane. Strangely enough the other problems I have had cycling around here is motorcycles; they love to hug the bike lanes and rev those loud things when they pass. Most regular bikers are pretty good folks but we get a lot of "Rolex-riders" that are responsible citizens back home, then they trailer there hardly-used Harleys on vacation behind their pricey SUV's to be big bad bikers dudes on vacation here. Real jerks!
Either way, they won't keep me off the road, maybe us "newbie's" will cross paths in our new life on the road