Would be no problem for me. Have not done more than four hours of harvesting without being shut down by rain yet this year. Maybe you have to just grease one side at a time every couple of hrs. or do the more important ones if there is such a thing, and leave the others for morning.
I agree that's ridiculous, our balzer is the same way recommending to grease every 4hrs. We usually only get it greased a couple times a week and it hasn't affected anything in the last 5 years or so but the track undercarriage must be different if it's already failing if you don't grease every 4 hrs of use.