I stay out of the fields when wet as I am on clay and clay doesn't forget.....sometimes it takes years to eliminate compaction caused by rolling on wet/soggy/damp fields. I understand you irony. Run it up and down the driveway, or think of some excuse to visit a neighbor down the road. Or just get it out on the road and run it. I do that in the winter when mine don't get used much. Keeps things lubed and limbered up. Also keeps the oil circulation so that the detergents and soot remain in suspense rather than settling to the bottom and making sludge from non use.
I have proven the above on two occasions. In one I had a covered, plastic container I used for a drain pan and for some reason didn't empty it.....maybe a year later I ran across it and the oil was relatively clear and the solids that were initially suspended in the (detergent) oil were on the bottom of the container.
The Ford 3910 I recently purchased, 1988 model with 900 hrs had the same problem. Upon receiving I changed the oil. I worked it hard for a couple of hours and the oil was already dirty. I drained the oil again and through the drain hole, mounted on the side of the pan, I could investigate the bottom of the pan and it had about a quarter inch of sludge just sitting there. I put in new oil and some snake oil and ran it over the same field in a second pass.
After that, while still hot I drained it again and this time there was no sludge on the bottom of the pan. New oil and filter and now the oil is clean when I check it.