For less than $200 I switched all 4 of mine. Was going to replace the shoes and for a little more i switched to the never adjust with all new assemblies. Not sure how it could cost more than disc brakes. I reused my old drums. So far so good.
Sounds like a good trip other than your mileage. I'm usually flirting with 12 mpg with my diesel. Gas is ~15% more expensive than diesel in California and my mileage increased ~50%. And diesels have a higher trade in/resale value so everything should be considered. And now I have the diesel grin. Towing is much more enjoyable.
I used to have a 2000 f250 and it started leaking on a trip at high temp. Got home and went to a Trans shop and he said the front seal ford used was garbage. Changed it and then no problems. Probably only had 30-40k on it then.
I had a 2000 f250 that leaked when I was towing. Made it home and went to a local transmission shop. It was the front seal. Shop owner said he got 1 ford a week with the same problem in the summer. He said the factory seals were crap. Fixed and never had another problem.