Merry X-Mas Oil Leak, Help

[G-Man]

So I had planned this wonderful Christmas vacation in So. Calif. with my newly purchased Gwagen. I must have been naughty, I'm wondering if this thing is the proverbial piece of coal for my stocking. First it ran rough, turned out to be a cracked plastic air tube between the MAF and throttle. Runs great now, except for a BIG leak. The shop that fixed the rough running said it was the rear crank seal, minor and don't worry yet. WRONG!! We drove 200 miles round trip to Disneyland yesterday. When we got there I noticed oil on the back of the truck. The whole underside took an oil bath, not to mention the whole back side of the truck. It appears to have lost over a half a quart in 200 miles. Not good considering I had planned to drive it 2000 miles home to Minnesota next week. Now what? Am I safe to drive it and add oil at every gas stop? Could this seal fail worse and strand me or cause major damage? I suspect I will have a very hard time getting it repaired next week with the holidays. Is this a known failure for a 65k mile M104? What is the approximate labor time for replacement? Any help is appreciated, Merry Christmas, Brent