Occasional front end "clunk" when towing with F250

[mikeinca]

I have a 2017 F250 diesel that I use to tow our 30' Classic. On occasion, on rougher roads, I'll get a clunking noise that sounds like it's coming from the truck's left front. The noise only seems to show up after a long towing day and with one exception....near the end of one long highway trip without the trailer.... manifests itself only when towing. Even then, it's usually after several hours and when ambient temps are high.

My suspicion is that the front shocks are getting overworked, are overheating and giving up a little. The truck only has about 8K miles on it so general front suspension wear wouldn't seem to be the issue. Any thoughts on alternative causes or has anyone had similar experiences?