Since you're not pulling a load, just idling along with lots of gears between the engine and the road, just overfill the crankcase by a couple of quarts and let the engine splash-lubricate itself. The oil pump will move enough oil to supply the rods and mains, and the pistons, rings and cam will get enough splash to survive. Just drain a little out before you get back on the road.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!