You're welcome, RareCJ8! Keep us posted, this hour meter idea makes great sense for a trail 4x4 vehicle. I gazed at hour meters for years as a heavy equipment operator, and the meters provided a valuable tool. Your lifeblood comment is real!
Synthetic oil provides a wider margin of oil protection; however, the oil filter needs attention. Many overlook the fact that an oil filter will bypass when clogged. Factory recommended 7,500 mile oil change intervals with tiny oil filters makes no sense at all. You cannot tell when the filter bypasses, so why run the risk?
On our vehicles with Mobil 1, which I started using in the early 'nineties, the oil color approach worked well. Engines like the '87 Suburban K2500's 350 V-8 with TBI would easily go 10,000-12,000 miles (highway use) on a crankcase of Mobil 1 oil, with oil filter changes and top-off with Mobil 1 (replenishes the oil's additives in the process) each 3,000-3,500 miles. On the carbureted '86 K2500 Suburban with Federal emissions and an unrestricted carburetor, the oil change interval would be much sooner when we pulled a trailer—more like an oil change right after each hard tow, according to oil color! This, again, was determined by oil coloration, mocha to dark mocha being the limit. I also used deeper "truck" application oil filters for added surface area and capacity. (You could do this on small-block Chevy V-8s with the vertical oil filter design.)
That method worked for me. Your hard trail use CJ8 Scrambler is a totally different scenario. The hour meter is the only sensible monitor.