Engine temp normal, but tranny running hot

Reasonably well-maintained car. Runs and performs well. Engine temp seems fine, and temp gauge seems to work correctly, never exceding even the halfway mark on the hottest days, and usually its about 35% to 40%. A couple of years ago, during warm months, I began to encounter very hard transmission shifting -- like with a real jerk -- in all gears as best I can recall. Felt like hot tranny problem to me, but I'm no expert. Attempted to drive at steady pace to minimize stops and starts. Found that I could drive five miles with no problem, park for an hour, start up and the hard shifts would be present. Finally, hit upon a very suboptimal and only partial solution. For the last two years, I have the A/C on at all times all year long. What this accomplishes is that the two cooling fans now run every second the car is on. Engine temp and temp gauge still seem to coincide. Appears to me that tranny temp is the issue, and the constant flow of air from the fans cools the tranny. So, now almost all of the time (except on the very hottest days, the tranny shifts without incident. No doubt the tranny has encountered some excess wear, but note that fluid has good color and the fluid does not smell burned. Generally, I only drive a few hundred miles a month, although last year, drove a 1,600 mile trip to the south with air temps in the 80's and 90's with no incident.

Any thoughts, ideas, suggestions, clues would be appreciated. I'm in my sixties, and pretty much past the point where I am able to do major, heavy automotive work in my garage, but I have no problem crawling under a properly supported vehicle and getting into stuff -- just not too much energy for wasted effort working on a car. Clearly, this vehicle is not worth much expense for professional repair, and, fortunately, I've been mostly able to avoid that about 45 years.

Thanks, guys.

Roger