"I can not think of any way to hurt a diesel more than not loading it once in awhile!" by which from context you seem to mean full throttle or near full throttle.

Does anyone have any data (I'm not taking about testimonials here) to support such an assertion? There are a tremendous number of over the road light diesels that *never* get operated any where near full throttle, pretty much none of them full throttle for an hour. It does not seem to hurt them or affect their service life. On my Ford truck, it is nearly impossible to operated it at full throttle for an hour. The rev limiter kicks in at a little over 100 mph, and it isn't anywhere near full power - maybe 50%. Towing a heavy trailer and finding a grade that takes an hour to climb isn't really practical once a month. Nobody does this, yet the engines keep running.

There is some reason to believe that idling one for hours on end might not be great for it - but as long as it sees enough load to get to proper operating temperature, I can see no argument that running it hard just for the sake of running it hard will do anything good. There is every reason to believe that running one at say 30% power for its life will make it last longer than running it at 80% power for its life. You can argue that this isn't economical: if you only needed 30% power, then buy a smaller engine and replace it when it is worn - but of course other considerations prevail.