I did too, I used to do a lot of white water and general multi-day adventure trips in my twenties but then we all started moving away and getting more heavily into other hobbies. We started flirting with it again recently with some over night trips and the Devils River multi-day a few months back and it has reignited the fire for a few of us. It's something a lot of our buddies can still justify doing at this point in their lives as it's not extremely physically taxing and the cost to entry barrier is all relative to what you're willing to spend. I would like to invest in a 14-16' touring kayak that can carry a lot of gear for multi-day trips on the rivers here in Texas.
At north of age 70, we are still able to do wilderness paddling trips because of not having to carry stuff on our backs very often. Having a background in climbing, backpacking, cycle touring, etc., really helps with kayaking trips at our age because, one; you probably have much of the needed gear laying around in your basement already and, two; you are probably already used to hard days, aches and pains and general short term discomfort from previous pursuits, knowing very well that these go away pretty quickly. The physical discomfort gets a bit more acute as you age but still well worth it!! We did a 1000 kilometer prairie river trip this summer and were noticeably physically stronger and lighter at the end, never a bad thing!! Here is a pic. As far as kayaks, you are right on with your size choice. We are good for easily 3 weeks between re-supplies, excluding water. Our boats are fairly hi-tec 15.5 ABS plastic. The NZ manufactured C-Tug wheels you see in the photo are gold for senior citizen portagers!!!!
